
_diffrn_orient_refln_angle_omega
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_omega'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_computing_cell_refinement
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_cell_refinement'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_refine_ls_extinction_expression
_category  refine 
_definition
 
;
A description or reference of the extinction correction equation
               used to apply the data item _refine_ls_extinction_coef. This
               information must be sufficient to reproduce the extinction
               correction factors applied to the structure factors.
;

_example
 
;
Larson, A. C. (1970). "Crystallographic Computing",
                             edited by F. R. Ahmed. Eq. (22) p. 292.
                             Copenhagen: Munksgaard.
;

_list  no 
_name '_refine_ls_extinction_expression'
_type  char 
_type_conditions  none 

_audit_contact_author_[]
_category 'category_overview'
_category.id 'audit_contact_author'
_definition
 
;
Data items in the AUDIT_CONTACT_AUTHOR category record details
               about the name and address of the author to be contacted
               concerning the contents of this data block.
;

_list  no 
_name '_audit_contact_author_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _audit_contact_author_name
    _audit_contact_author_address
    _audit_contact_author_email
    _audit_contact_author_fax
    _audit_contact_author_phone
        'Fitzgerald, Paula M. D.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
        'paula_fitzgerald@merck.com'
        '1(908)5945510'
        '1(908)5945510'
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

_refine_ls_class_R_factor_gt
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _refine_ls_class_wR_factor_all definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_R_factor_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_code_PDB
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_PDB'
_type  char 
_type_conditions  none 

_valence_ref_reference
_category 'valence_ref'
_definition
 
;
Literature reference from which the valence parameters
               identified by _valence_param_id were taken.
;

_list  yes 
_list_reference '_valence_ref_id'
_name '_valence_ref_reference'
_type  char 
_type_conditions  none 

_diffrn_reflns_transf_matrix_31
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_31'
_type  numb 
_type_conditions  none 

_journal_page_first
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_page_first'
_type  char 
_type_conditions  none 

_diffrn_reflns_transf_matrix_33
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_33'
_type  numb 
_type_conditions  none 

_diffrn_reflns_transf_matrix_32
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_32'
_type  numb 
_type_conditions  none 

_diffrn_reflns_class_d_res_high
_category 'diffrn_reflns_class'
_definition
 
;
The highest resolution in angstroms for the interplanar
               spacing in the reflections of each measured reflection class.
               This is the smallest d value for this reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_d_res_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_date_proofs_in
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_proofs_in'
_type  char 
_type_conditions  none 

_atom_site_occupancy
_category 'atom_site'
_definition
 
;
The fraction of the atom type present at this site.
               The sum of the occupancies of all the atom types at this site
               may not significantly exceed 1.0 unless it is a dummy site. The
               value must lie in the 99.97% Gaussian confidence interval
               -3u =< x =< 1 + 3u. The _enumeration_range of 0.0:1.0 is thus
               correctly interpreted as meaning (0.0 - 3u) =< x =< (1.0 + 3u).
;

_enumeration_default  1.0 
_enumeration_range  0.0:1.0 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_occupancy'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_diffrn_radiation_probe
_category 'diffrn_radiation'
_definition
 
;
The nature of the radiation used (i.e. name of subatomic particle
              or region of the electromagnetic spectrum). It is strongly
              encouraged that this field be specified so that the probe
              radiation can be simply determined.
;

_list  no 
_name '_diffrn_radiation_probe'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   x-ray 
   neutron 
   electron 
   gamma 

_computing_structure_solution
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_structure_solution'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_atom_site_aniso_ratio
_category 'atom_site'
_definition
 
;
Ratio of the maximum to minimum principal axes of
               displacement (thermal) ellipsoids.
;

_enumeration_range  1.0: 
_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_ratio'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_diffrn_refln_scan_time_backgd
_category 'diffrn_refln'
_definition 'The time spent measuring each background in seconds.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scan_time_backgd'
_type  numb 
_type_conditions  none 
_units  sec 
_units_detail  seconds 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_cell_reciprocal_angle_beta
_category  cell 
_definition
 
;
The angles in degrees defining the reciprocal cell. These
               are related to those in the real cell by:

               cos(recip-alpha)
                   = [cos(beta)*cos(gamma) - cos(alpha)]/[sin(beta)*sin(gamma)]

               cos(recip-beta)
                   = [cos(gamma)*cos(alpha) - cos(beta)]/[sin(gamma)*sin(alpha)]

               cos(recip-gamma)
                   = [cos(alpha)*cos(beta) - cos(gamma)]/[sin(alpha)*sin(beta)]

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_reciprocal_angle_beta'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_exptl_absorpt_correction_T_min
_category  exptl 
_definition
 
;
The maximum and minimum transmission factors for the crystal
                and radiation. These factors are also referred to as the
                absorption correction A or 1/A*.
;

_enumeration_range  0.0:1.0 
_list  no 
_name '_exptl_absorpt_correction_T_min'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_journal_suppl_publ_number
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_suppl_publ_number'
_type  char 
_type_conditions  none 

_atom_site_constraints
_category 'atom_site'
_definition
 
;
A description of the constraints applied to parameters at this
               site during refinement. See also _atom_site_refinement_flags
               and _refine_ls_number_constraints.
;

_enumeration_default  . 
_example  pop=1.0-pop(Zn3) 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_constraints'
_type  char 
_type_conditions  none 

_diffrn_orient_refln_angle_psi
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_psi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_diffrn_reflns_class_code
_category 'diffrn_reflns_class'
_definition 'The code identifying a certain reflection class.'
_list  yes 
_list_link_child '_diffrn_refln_class_code'
_list_mandatory  yes 
_name '_diffrn_reflns_class_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   m1 
   s2 

_cell_reciprocal_angle_gamma
_category  cell 
_definition
 
;
The angles in degrees defining the reciprocal cell. These
               are related to those in the real cell by:

               cos(recip-alpha)
                   = [cos(beta)*cos(gamma) - cos(alpha)]/[sin(beta)*sin(gamma)]

               cos(recip-beta)
                   = [cos(gamma)*cos(alpha) - cos(beta)]/[sin(gamma)*sin(alpha)]

               cos(recip-gamma)
                   = [cos(alpha)*cos(beta) - cos(gamma)]/[sin(alpha)*sin(beta)]

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_reciprocal_angle_gamma'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_citation_editor_ordinal
_category 'citation_editor'
_definition
 
;
This data name defines the order of the editor's name in the
               list of editors of a citation.
;

_list  yes 
_name '_citation_editor_ordinal'
_type  char 
_type_conditions  none 

_valence_param_B
_category 'valence_param'
_definition
 
;
The bond valence parameter B used in the expression

                     s = exp[(Ro - R)/B]

               where s is the valence of a bond of length R.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_B'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstrom 

_publ_[]
_category 'category_overview'
_category.id  publ 
_definition
 
;
Data items in the PUBL category are used when submitting a
               manuscript for publication. They refer either to the paper as
               a whole, or to specific named elements within a paper (such as
               the title and abstract, or the Comment and Experimental
               sections of Acta Crystallographica Section C). The data items
               in the PUBL_BODY category should be used for the textual
               content of other submissions. Typically, each journal will
               supply a list of the specific items it requires in its Notes
               for Authors.
;

_list  no 
_name '_publ_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_publ_section_title
    ;
        trans-3-Benzoyl-2-(tert-butyl)-4-(iso-butyl)-1,3-oxazolidin-5-one
    ;

    _publ_section_abstract
    ;  The oxazolidinone ring is a shallow envelope
       conformation with the tert-butyl and iso-butyl groups
       occupying trans-positions with respect to the ring. The
       angles at the N atom sum to 356.2\%, indicating a very
       small degree of pyramidalization at this atom. This is
       consistent with electron delocalization between the N
       atom and the carbonyl centre [N-C=O = 1.374(3)\%A].
    ;
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 
  
;
_publ_section_title
    ;   Hemiasterlin Methyl Ester
    ;

    _publ_section_title_footnote
    ;   IUPAC name: methyl 2,5-dimethyl-4-{2-[3-methyl-
        2-methylamino-3-(N-methylbenzo[b]pyrrol-
        3-yl)butanamido]-3,3-dimethyl-N-methyl-
        butanamido}-2-hexenoate.
    ;
;
  
;
Example 2 - based on C~31~H~48~N~4~O~4~, reported by Coleman, Patrick,
                Andersen & Rettig [(1996). Acta Cryst. C52, 1525-1527.
;
 

_atom_type_scat_Cromer_Mann_b4
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_b4'
_type  numb 
_type_conditions  none 

_symmetry_space_group_name_Hall
_category  symmetry 
_definition
 
;
Space-group symbol as described by Hall. This symbol gives the
               space-group setting explicitly. Leave spaces between the separate
               components of the symbol.

               Ref: Hall, S. R. (1981). Acta Cryst. A37, 517-525.
;

_list  no 
_name '_symmetry_space_group_name_Hall'
_related_function  replace 
_related_item '_space_group_name_Hall'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  '-P 2ac 2n'
  '-R 3 2"'
  'P 61 2 2 (0 0 -1)'

_diffrn_radiation_wavelength_wt
_category 'diffrn_radiation_wavelength'
_definition
 
;
The relative weight of a wavelength identified by the code
               _diffrn_radiation_wavelength_id in the list of wavelengths.
;

_enumeration_default  1.0 
_enumeration_range  0.0:1.0 
_list  yes 
_list_reference '_diffrn_radiation_wavelength_id'
_name '_diffrn_radiation_wavelength_wt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_audit_update_record
_category  audit 
_definition
 
;
A record of any changes to the data block. The update format
               is a date (yyyy-mm-dd) followed by a description of the
               changes. The latest update entry is added to the bottom of
               this record.
;

_example '1990-07-15   Updated by the Co-editor'
_list  no 
_name '_audit_update_record'
_type  char 
_type_conditions  none 

_atom_type_scat_Cromer_Mann_b2
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_b2'
_type  numb 
_type_conditions  none 

_reflns_shell_[]
_category 'category_overview'
_category.id 'reflns_shell'
_definition
 
;
Data items in the REFLNS_SHELL category record details about
               the reflections used to determine the ATOM_SITE data items,
               as broken down by shells of resolution.
;

_list  no 
_name '_reflns_shell_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _reflns_shell_d_res_high
    _reflns_shell_d_res_low
    _reflns_shell_meanI_over_uI_gt
    _reflns_shell_number_measured_gt
    _reflns_shell_number_unique_gt
    _reflns_shell_percent_possible_gt
    _reflns_shell_Rmerge_F_gt
      31.38  3.82  69.8  9024  2540  96.8   1.98
       3.82  3.03  26.1  7413  2364  95.1   3.85
       3.03  2.65  10.5  5640  2123  86.2   6.37
       2.65  2.41   6.4  4322  1882  76.8   8.01
       2.41  2.23   4.3  3247  1714  70.4   9.86
       2.23  2.10   3.1  1140   812  33.3  13.99
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

_geom_hbond_angle_DHA
_category 'geom_hbond'
_definition
 
;
Angle in degrees defined by the three sites
               _geom_hbond_atom_site_label_D, *_H and *_A. Site at *_D
               (the hydrogen atom participating in the interaction) is at
               the apex of the angle.
;

_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_angle_DHA'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

_refln_F_meas
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the structure factors (in electrons for
               X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_meas'
_type  numb 
_type_conditions  none 

_journal_paper_category
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_paper_category'
_type  char 
_type_conditions  none 

_citation_abstract_id_CAS
_category  citation 
_definition
 
;
The Chemical Abstracts Service (CAS) abstract identifier;
               relevant for journal articles.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_abstract_id_CAS'
_type  char 
_type_conditions  none 

_cell_special_details
_category  cell 
_definition
 
;
A description of special aspects of the cell choice, noting
               possible alternative settings.
;

_list  no 
_name '_cell_special_details'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   pseudo-orthorhombic 
  'standard setting from 45 deg rotation around c'

_geom_hbond_[]
_category 'category_overview'
_category.id 'geom_hbond'
_definition
 
;
Data items in the GEOM_HBOND category record details about
               hydrogen bonds, as calculated from the contents of the ATOM,
               CELL, and SYMMETRY data.
;

_list  no 
_name '_geom_hbond_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _geom_hbond_atom_site_label_D
    _geom_hbond_atom_site_label_H
    _geom_hbond_atom_site_label_A
    _geom_hbond_distance_DH
    _geom_hbond_distance_HA
    _geom_hbond_distance_DA
    _geom_hbond_angle_DHA
    _geom_hbond_publ_flag

    N6   HN6  OW   0.888(8)  1.921(12)  2.801(8)  169.6(8)  yes
    OW   HO2  O7   0.917(6)  1.923(12)  2.793(8)  153.5(8)  yes
    OW   HO1  N10  0.894(8)  1.886(11)  2.842(8)  179.7(9)  yes
;
  
;
Example 1 - based on C~14~H~13~ClN~2~O.H~2~O, reported by Palmer,
                Puddle & Lisgarten [(1993). Acta Cryst. C49, 1777-1779].
;
 

 loop_
   _category_mandatory.name                                                   
  '_geom_hbond_atom_site_label_H'
  '_geom_hbond_atom_site_label_A'
  '_geom_hbond_atom_site_label_D'

_atom_sites_Cartn_tran_matrix_23
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_23'
_type  numb 
_type_conditions  none 

_atom_type_scat_source
_category 'atom_type'
_definition
 
;
Reference to source of scattering factors or scattering lengths
               used for this atom type.
;

_example 'International Tables Vol. IV Table 2.4.6B'
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_source'
_type  char 
_type_conditions  none 

_refln_wavelength_id
_category  refln 
_definition
 
;
Code identifying the wavelength in the _diffrn_radiation_ list.
               See _diffrn_radiation_wavelength_id.
;

_list  yes 
_list_link_parent '_diffrn_radiation_wavelength_id'
_list_reference '_refln_index_'
_name '_refln_wavelength_id'
_type  char 
_type_conditions  none 

_diffrn_orient_matrix_[]
_category 'category_overview'
_category.id 'diffrn_orient_matrix'
_definition
 
;
Data items in the DIFFRN_ORIENT_MATRIX category record details
               about the orientation matrix used in data measurement.
;

_list  no 
_name '_diffrn_orient_matrix_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_orient_matrix_UB_11           -0.04170
    _diffrn_orient_matrix_UB_12           -0.01429
    _diffrn_orient_matrix_UB_13           -0.02226
    _diffrn_orient_matrix_UB_21           -0.00380
    _diffrn_orient_matrix_UB_22           -0.05578
    _diffrn_orient_matrix_UB_23           -0.05048
    _diffrn_orient_matrix_UB_31            0.00587
    _diffrn_orient_matrix_UB_32           -0.13766
    _diffrn_orient_matrix_UB_33            0.02277

    _diffrn_orient_matrix_type             'TEXSAN convention (MSC, 1989)'
;
  
;
Example 1 - data set n-alkylation_C-4 of Hussain, Fleming, Norman & Chang
                [(1996). Acta Cryst. C52, 1010-1012].
;
 

_citation_journal_abbrev
_category  citation 
_definition
 
;
Abbreviated name of the journal cited as given in the Chemical
               Abstracts Service Source Index.
;

_example 'J. Mol. Biol.'
_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_abbrev'
_type  char 
_type_conditions  none 

_chemical_conn_atom_number
_category 'chemical_conn_atom'
_definition 'The chemical sequence number to be associated with this atom.'
_enumeration_range  1: 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_number'
_type  numb 
_type_conditions  none 

 loop_
   _list_link_child                                                           
  '_atom_site_chemical_conn_number'
  '_chemical_conn_bond_atom_1'
  '_chemical_conn_bond_atom_2'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_refln_sint/lambda
_category  refln 
_definition
 
;
The (sin theta)/lambda value in reciprocal angstroms for this
               reflection.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_sint/lambda'
_type  numb 
_type_conditions  none 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_conn_atom_NH
_category 'chemical_conn_atom'
_definition
 
;
The total number of hydrogen atoms attached to this atom,
               regardless of whether they are included in the refinement or
               the _atom_site_ list. This number will be the same as
               _atom_site_attached_hydrogens only if none of the hydrogen
               atoms appear in the _atom_site_ list.
;

_enumeration_range  0: 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_NH'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_symmetry_epsilon
_category  refln 
_definition
 
;
The symmetry reinforcement factor corresponding to the number of
               times the reflection indices are generated identically from the
               space-group symmetry operations.
;

_enumeration_range  1:48 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_symmetry_epsilon'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   48.0   48.0 
   48.0   1.0 
   1.0   1.0 

_exptl_crystal_face_index_l
_category 'exptl_crystal_face'
_definition
 
;
Miller indices of the crystal face associated with the value
               _exptl_crystal_face_perp_dist.
;

_list  yes 
_list_mandatory  yes 
_name '_exptl_crystal_face_index_l'
_type  numb 
_type_conditions  none 

_exptl_crystal_face_index_k
_category 'exptl_crystal_face'
_definition
 
;
Miller indices of the crystal face associated with the value
               _exptl_crystal_face_perp_dist.
;

_list  yes 
_list_mandatory  yes 
_name '_exptl_crystal_face_index_k'
_type  numb 
_type_conditions  none 

_publ_requested_journal
_category  publ 
_definition
 
;
The name of the journal to which the manuscript is being
               submitted.
;

_list  no 
_name '_publ_requested_journal'
_type  char 
_type_conditions  none 

_cell_length_a
_category  cell 
_definition
 
;
Unit-cell lengths in angstroms corresponding to the structure
               reported. The values of _refln_index_h, *_k, *_l must
               correspond to the cell defined by these values and _cell_angle_
               values. The values of _diffrn_refln_index_h, *_k, *_l may not
               correspond to these values if a cell transformation took place
               following the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_length_a'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_U_equiv_geom_mean
_category 'atom_site'
_definition
 
;
Equivalent isotropic atomic displacement parameter, U(equiv),
               in angstroms squared, calculated as the geometric mean of
               the anisotropic atomic displacement parameters.

               U(equiv) = (U~i~ U~j~ U~k~)^1/3^

               U~n~  = the principal components of the orthogonalised U^ij^
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_U_equiv_geom_mean'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_atom_site_U_iso_or_equiv'
   conversion  '_atom_site_B_equiv_geom_mean'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_[]
_category 'category_overview'
_category.id  database 
_definition
 
;
Data items in the DATABASE category record details about the
               database identifiers of the data block.

               These data items are assigned by database managers and should
               only appear in a CIF if they originate from that source.
;

_list  no 
_name '_database_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  "_database_code_CSD                  'VOBYUG'" 
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_publ_body_label
_category 'publ_body'
_definition
 
;
Code identifying the section of text. The combination of this
               with _publ_body_element must be unique.
;

_list  yes 
_list_mandatory  yes 
_list_uniqueness '_publ_body_element'
_name '_publ_body_label'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   1.1 
   2.1.3 

_diffrn_refln_standard_code
_category 'diffrn_refln'
_definition
 
;
A code identifying that this reflection was measured as a
               standard intensity. The value must be '.' or match one of
               the _diffrn_standard_refln_code values.
;

_list  yes 
_list_link_parent '_diffrn_standard_refln_code'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_standard_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   2 
   3 
   s1 
   s2 
   s3 
   A 
   B 
   C 

_exptl_crystal_description
_category 'exptl_crystal'
_definition
 
;
A description of the quality and habit of the crystal.
               The crystal dimensions should not normally be reported here;
               use instead _exptl_crystal_size_ for the gross dimensions of
               the crystal, and _exptl_crystal_face_ to describe the
               relationship between individual faces.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_description'
_type  char 
_type_conditions  none 

_diffrn_attenuator_[]
_category 'category_overview'
_category.id 'diffrn_attenuator'
_definition
 
;
Data items in the DIFFRN_ATTENUATOR category record details
               about the diffraction attenuator scales employed.
;

_list  no 
_name '_diffrn_attenuator_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
        _diffrn_attenuator_code
        _diffrn_attenuator_scale       1     16.976
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_diffrn_attenuator_code'

_cell_length_b
_category  cell 
_definition
 
;
Unit-cell lengths in angstroms corresponding to the structure
               reported. The values of _refln_index_h, *_k, *_l must
               correspond to the cell defined by these values and _cell_angle_
               values. The values of _diffrn_refln_index_h, *_k, *_l may not
               correspond to these values if a cell transformation took place
               following the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_length_b'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_book_publisher_city
_category  citation 
_definition
 
;
The location of the publisher of the citation; relevant
               for book chapters.
;

_example 'New York'
_list  yes 
_list_reference '_citation_id'
_name '_citation_book_publisher_city'
_type  char 
_type_conditions  none 

_refine_ls_wR_factor_obs
_category  refine 
_definition
 
;
Weighted residual factors for the reflections classified as
               'observed' (see _reflns_observed_criterion) and included
               in the refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_wR_factor_obs'
_related_function  replace 
_related_item '_refine_ls_wR_factor_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_refinement_flags_adp
_category 'atom_site'
_definition
 
;
A code which indicates the refinement restraints or constraints
               applied to the atomic displacement parameters of this site.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_refinement_flags_adp'
_related_function  alternate 
_related_item '_atom_site_refinement_flags_posn'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   .  'no constraints on atomic displacement parameters'
   T  'special-position constraints on atomic displacement parameters'
   U  'Uiso or Uij restraint (rigid bond)'
   TU  'Both constraints applied'

_citation_editor_citation_id
_category 'citation_editor'
_definition
 
;
The value of _citation_editor_citation_id must match an
               identifier specified by _citation_id in the _citation_ list.
;

_list  yes 
_list_link_parent '_citation_id'
_list_mandatory  yes 
_name '_citation_editor_citation_id'
_type  char 
_type_conditions  none 

_publ_section_title_footnote
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_title_footnote'
_type  char 
_type_conditions  none 

_diffrn_standards_decay_%
_category 'diffrn_standards'
_definition
 
;
The percentage decrease in the mean of the intensities
               for the set of standard reflections at the start of the
               measurement process and at the finish. This value usually
               affords a measure of the overall decay in crystal quality
               during the diffraction measurement process. Negative values
               are used in exceptional instances where the final intensities
               are greater than the initial ones.
;

_enumeration_range  :100 
_list  no 
_name '_diffrn_standards_decay_%'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   100.0   100.0 
   100.0   . 

_refine_ls_extinction_coef
_category  refine 
_definition
 
;
The extinction coefficient used to calculate the correction
               factor applied to the structure-factor data. The nature of the
               extinction coefficient is given in the definitions of
               _refine_ls_extinction_expression and
               _refine_ls_extinction_method.

               For the 'Zachariasen' method it is the r* value; for the
               'Becker-Coppens type 1 isotropic' method it is the 'g' value,
               and for 'Becker-Coppens type 2 isotropic' corrections it is
               the 'rho' value. Note that the magnitude of these values is
               usually of the order of 10000.

               Ref:  Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30,
                     129-153.
                     Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
                     Larson, A. C. (1967). Acta Cryst. 23, 664-665.
;

_example  3472(52) 
_example_detail 'Zachariasen coefficient r* = 0.347(5) E04'
_list  no 
_name '_refine_ls_extinction_coef'
_type  numb 
_type_conditions  esd 

_space_group_symop_[]
_category 'category_overview'
_category.id 'space_group_symop'
_definition
 
;
Contains information about the symmetry operations of the
               space group.
;

_list  no 
_name '_space_group_symop_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _space_group_symop_id
    _space_group_symop_operation_xyz
      1    x,y,z          
      2   -x,-y,-z        
      3   -x,1/2+y,1/2-z  
      4    x,1/2-y,1/2+z  
;
  'Example 1 - The symmetry operations for the space group P21/c.'

 loop_
   _category_mandatory.name                                                   
  '_space_group_symop_id'

_cell_measurement_refln_index_k
_category 'cell_measurement_refln'
_definition
 
;
Miller indices of a reflection used for measurement of
               the unit cell.
;

_list  yes 
_list_mandatory  yes 
_name '_cell_measurement_refln_index_k'
_type  numb 
_type_conditions  none 

_publ_section_references
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_references'
_type  char 
_type_conditions  none 

_atom_sites_fract_tran_matrix_12
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_12'
_type  numb 
_type_conditions  none 

_reflns_shell_Rmerge_I_all
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(I) for all reflections in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_I_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_section_exptl_prep
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_exptl_prep'
_type  char 
_type_conditions  none 

_refine_ls_wR_factor_gt
_category  refine 
_definition
 
;
Weighted residual factors for significantly intense reflections
               (satisfying _reflns_threshold_expression) included in the
               refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low.  See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_wR_factor_gt'
_related_function  alternate 
_related_item '_refine_ls_wR_factor_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_crystal_colour_primary
_category 'exptl_crystal'
_definition
 
;
The enumeration list of standardized names developed for the
              International Center for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green', 
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_colour_primary'
_related_function  alternate 
_related_item '_exptl_crystal_colour'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   colourless 
   white 
   black 
   gray 
   brown 
   red 
   pink 
   orange 
   yellow 
   green 
   blue 
   violet 

_geom_torsion_[]
_category 'category_overview'
_category.id 'geom_torsion'
_definition
 
;
Data items in the GEOM_TORSION category record details about
               interatomic torsion angles, as calculated from the contents of
               the ATOM, CELL, and SYMMETRY data.
;

_list  no 
_name '_geom_torsion_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
     _geom_torsion_atom_site_label_1
     _geom_torsion_atom_site_label_2
     _geom_torsion_atom_site_label_3
     _geom_torsion_atom_site_label_4
     _geom_torsion
     _geom_torsion_site_symmetry_1
     _geom_torsion_site_symmetry_2
     _geom_torsion_site_symmetry_3
     _geom_torsion_site_symmetry_4
     _geom_torsion_publ_flag
     C(9)  O(2)  C(7)   C(2)    71.8(2)  .  .  .  .      yes
     C(7)  O(2)  C(9)   C(10) -168.0(3)  .  .  .  2_666  yes
     C(10) O(3)  C(8)   C(6)  -167.7(3)  .  .  .  .      yes
     C(8)  O(3)  C(10)  C(9)   -69.7(2)  .  .  .  2_666  yes
     O(1)  C(1)  C(2)   C(3)  -179.5(4)  .  .  .  .      no
     O(1)  C(1)  C(2)   C(7)    -0.6(1)  .  .  .  .      no
;
  
;
Example 1 - based on data set CLPHO6 of Ferguson, Ruhl, McKervey & Browne
                [(1991). Acta Cryst. C48, 2262-2264].
;
 

 loop_
   _category_mandatory.name                                                   
  '_geom_torsion_atom_site_label_4'
  '_geom_torsion_atom_site_label_1'
  '_geom_torsion_atom_site_label_3'
  '_geom_torsion_atom_site_label_2'

_reflns_limit_h_min
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_h_min'
_type  numb 
_type_conditions  none 

_reflns_observed_criterion
_category  reflns 
_definition
 
;
The criterion used to classify a reflection as 'observed'. This
               criterion is usually expressed in terms of a sigma(I) or sigma(F)
               threshold.
;

_example  I>2u(I) 
_list  no 
_name '_reflns_observed_criterion'
_related_function  replace 
_related_item '_reflns_threshold_expression'
_type  char 
_type_conditions  none 

_journal_date_printers_first
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_printers_first'
_type  char 
_type_conditions  none 

_refine_ls_hydrogen_treatment
_category  refine 
_definition 'Treatment of hydrogen atoms in the least-squares refinement.'
_enumeration_default  undef 
_list  no 
_name '_refine_ls_hydrogen_treatment'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   refall  'refined all H parameters'
   refxyz  'refined H coordinates only'
   refU  'refined H U only'
   noref  'no refinement of H parameters'
   constr  'H parameters constrained'
   mixed  'some constrained, some independent'
   undef  'H-atom parameters not defined'

_chemical_formula_moiety
_category 'chemical_formula'
_definition
 
;
Formula with each discrete bonded residue or ion shown as a
               separate moiety. See above _chemical_formula_[] for rules
               for writing chemical formulae. In addition to the general
               formulae requirements, the following rules apply:
                  1. Moieties are separated by commas ','.
                  2. The order of elements within a moiety follows general rule
                     5 in _chemical_formula_[].
                  3. Parentheses are not used within moieties but may surround
                     a moiety. Parentheses may not be nested.
                  4. Charges should be placed at the end of the moiety. The
                     charge '+' or '-' may be preceded by a numerical multiplier
                     and should be separated from the last (element symbol +
                     count) by a space. Pre- or post-multipliers may be used for
                     individual moieties.
;

_list  no 
_name '_chemical_formula_moiety'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'C7 H4 Cl Hg N O3 S'
  'C12 H17 N4 O S 1+, C6 H2 N3 O7 1-'
  'C12 H16 N2 O6, 5(H2 O1)'
  '(Cd 2+)3, (C6 N6 Cr 3-)2, 2(H2 O)'

_exptl_crystal_id
_category 'exptl_crystal'
_definition
 
;
Code identifying each crystal if multiple crystals are used. It
               is used to link with _diffrn_refln_crystal_id in intensity
               measurement and with _refln_crystal_id in the _refln_ list.
;

_list  yes 
_list_mandatory  yes 
_name '_exptl_crystal_id'
_type  char 
_type_conditions  none 

 loop_
   _list_link_child                                                           
  '_diffrn_refln_crystal_id'
  '_refln_crystal_id'

_reflns_shell_d_res_low
_category 'reflns_shell'
_definition
 
;
The lowest resolution in angstroms for the interplanar spacing
               in the reflections in this shell. This is the largest d value.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_d_res_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_type_number_in_cell
_category 'atom_type'
_definition 'Total number of atoms of this atom type in the unit cell.'
_enumeration_range  0: 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_number_in_cell'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_link_block_description
_category 'audit_link'
_definition
 
;
A textual description of the relationship of the referenced
               data block to the current one.
;

_list  yes 
_list_reference '_audit_link_block_code'
_name '_audit_link_block_description'
_type  char 
_type_conditions  none 

_refine_ls_abs_structure_Flack
_category  refine 
_definition
 
;
The measure of absolute structure as defined by Flack.

               For centrosymmetric structures the only permitted value, if the
               data name is present, is 'inapplicable' represented by '.' .

               For non-centrosymmetric structures the value must lie in the
               99.97% Gaussian confidence interval  -3u =< x =< 1 + 3u and a
               standard uncertainty (e.s.d.) u must be supplied. The
               _enumeration_range of 0.0:1.0 is correctly interpreted as
               meaning (0.0 - 3u) =< x =< (1.0 + 3u).

               Ref: Flack, H. D. (1983). Acta Cryst. A39, 876-881.
;

_enumeration_range  0.0:1.0 
_list  no 
_name '_refine_ls_abs_structure_Flack'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_chemical_[]
_category 'category_overview'
_category.id  chemical 
_definition
 
;
Data items in the CHEMICAL category record details about the
               composition and chemical properties of the compounds. The
               formula data items must agree with those that specify the
               density, unit-cell and Z values.
;

_list  no 
_name '_chemical_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_chemical_name_systematic
         trans-bis(tricyclohexylphosphine)tetracarbonylmolybdenum(0)
;
  
;
Example 1 - based on data set 9597gaus of Alyea, Ferguson & Kannan [(1996).
                Acta Cryst. C52, 765-767].
;
 

_refln_symmetry_multiplicity
_category  refln 
_definition
 
;
The number of reflections symmetry-equivalent under the Laue
               symmetry to the present reflection. In the Laue symmetry, Friedel
               opposites (h k l and -h -k -l) are equivalent. Tables of
               symmetry-equivalent reflections are available in International
               Tables for Crystallography, Volume A (1987), section 10.2.
;

_enumeration_range  1:48 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_symmetry_multiplicity'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   48.0   48.0 
   48.0   1.0 
   1.0   1.0 

_atom_site_disorder_group
_category 'atom_site'
_definition
 
;
A code that identifies a group of positionally disordered atom
               sites that are locally simultaneously occupied. Atoms that are
               positionally disordered over two or more sites (e.g. the H
               atoms of a methyl group that exists in two orientations) can
               be assigned to two or more groups. Sites belonging to the same
               group are simultaneously occupied, but those belonging to
               different groups are not. A minus prefix (e.g. "-1") is used to
               indicate sites disordered about a special position.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_disorder_group'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   1  'unique disordered site in group 1'
   2  'unique disordered site in group 2'
   -1  'symmetry-independent disordered site'

_refln_B_calc
_category  refln 
_definition
 
;
The calculated and measured structure-factor component B
               (in electrons for X-ray diffraction).

               B =|F|sin(phase)
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_B_calc'
_type  numb 
_type_conditions  none 

_citation_special_details
_category  citation 
_definition
 
;
A description of special aspects that describe the relationship
               of the contents of the data block to the literature item cited.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_special_details'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'citation relates to this precise coordinate set'
  'citation relates to earlier low-resolution structure'
  
;
citation relates to further refinement of structure
                        reported in citation 2
;
 

_reflns_special_details
_category  reflns 
_definition
 
;
Description of the properties of the reported reflection list
               that is not given in other data items.  In particular it should
               include information about the averaging (or not) of
               symmetry-equivalent reflections including Friedel pairs.
;

_list  no 
_name '_reflns_special_details'
_type  char 
_type_conditions  none 

_refln_phase_meas
_category  refln 
_definition 'The measured structure-factor phase in degrees.'
_list  yes 
_list_reference '_refln_index_'
_name '_refln_phase_meas'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

_atom_type_scat_Cromer_Mann_a3
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_a3'
_type  numb 
_type_conditions  none 

_refine_ls_wR_factor_ref
_category  refine 
_definition
 
;
Weighted residual factors for all reflections included in the
               refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low.  See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_wR_factor_ref'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_index_term
_category 'journal_index'
_definition 'Indexing terms supplied by journals staff.'
_list  no 
_name '_journal_index_term'
_type  char 
_type_conditions  none 

_atom_site_B_equiv_geom_mean
_category 'atom_site'
_definition
 
;
Equivalent isotropic atomic displacement parameter, B(equiv),
               in angstroms squared, calculated as the geometric mean of
               the anisotropic atomic displacement parameters.

               B(equiv) = (B~i~ B~j~ B~k~)^1/3^

               B~n~  = the principal components of the orthogonalised B^ij^

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_B_equiv_geom_mean'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_atom_site_B_iso_or_equiv'
   conversion  '_atom_site_U_equiv_geom_mean'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_number_measured_gt
_category 'reflns_shell'
_definition
 
;
The number of significantly intense reflections
               (see _reflns_threshold_expression) measured for this
               resolution shell.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_number_measured_gt'
_related_function  alternate 
_related_item '_reflns_shell_number_measured_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_angle_kappa
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_kappa'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_atom_site_Wyckoff_symbol
_category 'atom_site'
_definition
 
;
The Wyckoff symbol (letter) as listed in the space-group section
               of International Tables for Crystallography, Vol. A (1987).
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_Wyckoff_symbol'
_type  char 
_type_conditions  none 

_atom_sites_special_details
_category 'atom_sites'
_definition
 
;
Additional information about the atomic coordinates not coded
               elsewhere in the CIF.
;

_list  no 
_name '_atom_sites_special_details'
_type  char 
_type_conditions  none 

_diffrn_ambient_pressure
_category  diffrn 
_definition
 
;
The mean hydrostatic pressure in kilopascals at which the
               intensities were measured.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_pressure'
_type  numb 
_type_conditions  esd 
_units  kPa 
_units_detail  kilopascals 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_F_squared_meas
_category  refln 
_definition
 
;
Calculated, measured and estimated standard uncertainty (derived
               from measurement) of the squared structure factors (in electrons
               squared for X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_squared_meas'
_type  numb 
_type_conditions  none 

_diffrn_refln_angle_psi
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_psi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_valence_ref_[]
_category 'category_overview'
_category.id 'valence_ref'
_definition
 
;
Data items in the VALENCE_REF category list the references
               from which the bond valence parameters have been taken.
;

_list  no 
_name '_valence_ref_[]'
_type  null 
_type_conditions  none 

_citation_journal_issue
_category  citation 
_definition
 
;
Issue number of the journal cited;  relevant for journal
               articles.
;

_example  2 
_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_issue'
_type  char 
_type_conditions  none 

_geom_torsion_atom_site_label_4
_category 'geom_torsion'
_definition
 
;
The labels of the four atom sites which define the torsion angle
               specified by _geom_torsion. These must match codes specified as
               _atom_site_label in the atom list. The torsion angle definition
               should be that of Klyne and Prelog. The vector direction
               *_label_2 to *_label_3 is the viewing direction, and the torsion
               angle is the angle of twist required to superimpose the
               projection of the vector site2-site1 onto the projection of the
               vector site3-site4. Clockwise torsions are positive,
               anticlockwise torsions are negative.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_torsion_atom_site_label_4'
_type  char 
_type_conditions  none 

_geom_torsion_atom_site_label_1
_category 'geom_torsion'
_definition
 
;
The labels of the four atom sites which define the torsion angle
               specified by _geom_torsion. These must match codes specified as
               _atom_site_label in the atom list. The torsion angle definition
               should be that of Klyne and Prelog. The vector direction
               *_label_2 to *_label_3 is the viewing direction, and the torsion
               angle is the angle of twist required to superimpose the
               projection of the vector site2-site1 onto the projection of the
               vector site3-site4. Clockwise torsions are positive,
               anticlockwise torsions are negative.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_torsion_atom_site_label_1'
_type  char 
_type_conditions  none 

_geom_torsion_atom_site_label_3
_category 'geom_torsion'
_definition
 
;
The labels of the four atom sites which define the torsion angle
               specified by _geom_torsion. These must match codes specified as
               _atom_site_label in the atom list. The torsion angle definition
               should be that of Klyne and Prelog. The vector direction
               *_label_2 to *_label_3 is the viewing direction, and the torsion
               angle is the angle of twist required to superimpose the
               projection of the vector site2-site1 onto the projection of the
               vector site3-site4. Clockwise torsions are positive,
               anticlockwise torsions are negative.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_torsion_atom_site_label_3'
_type  char 
_type_conditions  none 

_chemical_formula_weight
_category 'chemical_formula'
_definition
 
;
Formula mass in daltons. This mass should correspond to the
               formulae given under _chemical_formula_structural, *_iupac,
               *_moiety or *_sum and, together with the Z value and cell
               parameters, should yield the density given as
               _exptl_crystal_density_diffrn.
;

_enumeration_range  1.0: 
_list  no 
_name '_chemical_formula_weight'
_type  numb 
_type_conditions  none 
_units  Da 
_units_detail  daltons 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_diffrn_scale_group_I_net
_category 'diffrn_scale_group'
_definition
 
;
The scale for a specific measurement group which is to be
               multiplied with the net intensity to place all intensities
               in the _diffrn_refln_ or _refln_ list on a common scale.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_scale_group_code'
_name '_diffrn_scale_group_I_net'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_scan_width
_category 'diffrn_refln'
_definition
 
;
The scan width in degrees of the scan mode defined by the code
               _diffrn_refln_scan_mode.
;

_enumeration_range  0.0:90.0 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scan_width'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_valence_ref_id
_category 'valence_ref'
_definition
 
;
An identifier for items in this category. Parent of
               _valence_param_ref_id which must have the same value.
;

_list  yes 
_list_link_child '_valence_param_ref_id'
_list_reference '_valence_ref_id'
_name '_valence_ref_id'
_type  char 
_type_conditions  none 

_category_overview_[]
_category 'category_overview'
_category.id 'category_overview'
_type  null 

_reflns_limit_l_min
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_l_min'
_type  numb 
_type_conditions  none 

_cell_measurement_theta_min
_category  cell 
_definition
 
;
The maximum and minimum theta angles in degrees of reflections
               used to measure the unit cell.
;

_enumeration_range  0.0:90.0 
_list  no 
_name '_cell_measurement_theta_min'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_publ_body_element
_category 'publ_body'
_definition 'The functional role of the associated text section.'
_list  yes 
_list_reference '_publ_body_label'
_name '_publ_body_element'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   section 
   subsection 
   subsubsection 
   appendix 
   footnote 

_exptl_absorpt_coefficient_mu
_category  exptl 
_definition
 
;
The absorption coefficient mu in reciprocal millimetres
               calculated from the atomic content of the cell, the density and
               the radiation wavelength.
;

_enumeration_range  0.0: 
_list  no 
_name '_exptl_absorpt_coefficient_mu'
_type  numb 
_type_conditions  none 
_units  mm^-1^ 
_units_detail 'reciprocal millimetres'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_radiation_type
_category 'diffrn_radiation'
_definition
 
;
The type of the radiation. This represents a finer-grained
               level of description than _diffrn_radiation_probe and is
               typically a description of the X-ray wavelength in Siegbahn
               notation.
;

_list  no 
_name '_diffrn_radiation_type'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Cu K\a'
  'Cu K\a~1~'
  'Cu K-L~2,3~'
   white-beam 

_geom_bond_site_symmetry_1
_category 'geom_bond'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the bond. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_bond_atom_site_label_'
_name '_geom_bond_site_symmetry_1'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_chemical_name_systematic
_category  chemical 
_definition 'IUPAC or Chemical Abstracts full name of compound.'
_example  1-bromoestra-1,3,5(10)-triene-3,17\b-diol 
_list  no 
_name '_chemical_name_systematic'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_11
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_11'
_type  numb 
_type_conditions  none 

_diffrn_symmetry_description
_category  diffrn 
_definition
 
;
Observed diffraction point symmetry, systematic absences and
               possible space group(s) or superspace group(s) compatible with
               these.
;

_list  no 
_name '_diffrn_symmetry_description'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_13
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_13'
_type  numb 
_type_conditions  none 

_space_group_[]
_category 'category_overview'
_category.id 'space_group'
_definition
 
;
Contains all the data items that refer to the space group as a
               whole, such as its name, crystal system etc. It may be looped,
               for example, in a list of space groups and their properties.

               Only a subset of the SPACE_GROUP category items appear in the 
               core dictionary.  The remainder are found in the cif_sym
               dictionary.

               Space group types are identified by their International Tables
               for Crystallography Vol. A number. Specific settings of the
               space groups can be identified either by their Hall symbol
               or by specifying their symmetry operations.

               The commonly-used Hermann-Mauguin symbol determines the
               space group type uniquely but several different Hermann-Mauguin
               symbols may refer to the same space group type. It contains
               information on the choice of the basis, but not on the
               choice of origin.  Different formats for the Hermann-Mauguin
               symbol are found in the cif_sym dictionary.
;

_list  no 
_name '_space_group_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_space_group_id                 1
    _space_group_name_H-M_alt       'C 2/c'
    _space_group_IT_number          15
    _space_group_name_Hall          '-C 2yc'
    _space_group_crystal_system     monoclinic
;
  'Example 1 - The monoclinic space group no. 15 with unique axis b.'

 loop_
   _category_mandatory.name                                                   
  '_space_group_id'

_diffrn_refln_counts_bg_1
_category 'diffrn_refln'
_definition
 
;
The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_counts_bg_1'
_type  numb 
_type_conditions  none 

_chemical_temperature_decomposition_lt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above which
               (*_gt) the solid is known to decompose. These items allow
               a range of temperatures to be given. 

               _chemical_temperature_decomposition should always be used in
               preference to these items whenever possible.
;

_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_decomposition_lt'
_related_function  alternate 
_related_item '_chemical_temperature_decomposition'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_formula_[]
_category 'category_overview'
_category.id 'chemical_formula'
_definition
 
;
_chemical_formula_ items specify the composition and chemical
              properties of the compound. The formula data items must agree
              with those that specify the density, unit-cell and Z values.

              The following rules apply to the construction of the data items
              _chemical_formula_analytical, *_structural and *_sum. For the
              data item *_moiety the formula construction is broken up into
              residues or moieties, i.e. groups of atoms that form a molecular
              unit or molecular ion. The  rules given below apply within each
              moiety but different requirements apply to the way that moieties
              are connected (see _chemical_formula_moiety).

              1. Only recognized element symbols may be used.

              2. Each element symbol is followed by a 'count' number. A count of
                 '1' may be omitted.

              3. A space or parenthesis must separate each cluster of (element
                 symbol + count).

              4. Where a group of elements is enclosed in parentheses, the
                 multiplier for the group must follow the closing parentheses.
                 That is, all element and group multipliers are assumed to be
                 printed as subscripted numbers. [An exception to this rule
                 exists for *_moiety formulae where pre- and post-multipliers
                 are permitted for molecular units].

              5. Unless the elements are ordered in a manner that corresponds to
                 their chemical structure, as in _chemical_formula_structural,
                 the order of the elements within any group or moiety
                 depends on whether or not carbon is present. If carbon is
                 present, the order should be: C, then H, then the other
                 elements in alphabetical order of their symbol. If carbon is
                 not present, the elements are listed purely in alphabetic order
                 of their symbol. This is the 'Hill' system used by Chemical
                 Abstracts. This ordering is used in _chemical_formula_moiety
                 and _chemical_formula_sum.
;

_list  no 
_name '_chemical_formula_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_chemical_formula_moiety            'C18 H25 N O3'
    _chemical_formula_sum               'C18 H25 N O3'
    _chemical_formula_weight            303.40
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 
  
;
_chemical_formula_iupac      '[Mo (C O)4 (C18 H33 P)2]'
    _chemical_formula_moiety     'C40 H66 Mo O4 P2'
    _chemical_formula_structural '((C O)4 (P (C6 H11)3)2)Mo'
    _chemical_formula_sum         'C40 H66 Mo O4 P2'
    _chemical_formula_weight      768.81
;
  
;
Example 2 - based on data set 9597gaus of Alyea, Ferguson & Kannan [(1996).
                Acta Cryst. C52, 765-767].
;
 

_space_group_symop_operation_xyz
_category 'space_group_symop'
_definition
 
;
A parsable string giving one of the symmetry operations of the
                space group in algebraic form.  If W is a matrix representation
                of the rotational part of the symmetry operation defined by the
                positions and signs of x, y and z, and w is a column of
                translations defined by the fractions, an equivalent position
                X' is generated from a given position X by the equation:

                          X' = WX + w

                (Note: X is used to represent bold_italics_x in International
                Tables for Crystallography Vol. A, Section 5)

                When a list of symmetry operations is given, it must contain
                a complete set of coordinate representatives which generates
                all the operations of the space group by the addition of
                all primitive translations of the space group. Such
                representatives are to be found as the coordinates of
                the general-equivalent position in International Tables for
                Crystallography Vol. A, to which it is necessary to add any
                centring translations shown above the general-equivalent
                position.

                That is to say, it is necessary to list explicity all the
                symmetry operations required to generate all the atoms in
                the unit cell defined by the setting used. 
;

_enumeration_default  x,y,z 
_list  both 
_list_reference '_space_group_symop_id'
_name '_space_group_symop_operation_xyz'
_related_function  alternate 
_related_item '_symmetry_equiv_pos_as_xyz'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   x,1/2-y,1/2+z  
;
glide reflection through the plane (x,1/4,z),
                                 with glide vector 1/2 c
;
 

_reflns_scale_meas_F_squared
_category 'reflns_scale'
_definition 'Scales associated with _reflns_scale_group_code.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_scale_group_code'
_name '_reflns_scale_meas_F_squared'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_cell_[]
_category 'category_overview'
_category.id  cell 
_definition
 
;
Data items in the CELL category record details about the
               crystallographic cell parameters and their measurement.
;

_list  no 
_name '_cell_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_cell_length_a                     5.959(1)
    _cell_length_b                     14.956(1)
    _cell_length_c                     19.737(3)
    _cell_angle_alpha                  90
    _cell_angle_beta                   90
    _cell_angle_gamma                  90
    _cell_volume                       1759.0(3)

    _cell_measurement_temperature      293
    _cell_measurement_reflns_used      25
    _cell_measurement_theta_min        25
    _cell_measurement_theta_max        31
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_chemical_temperature_decomposition_gt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above which
               (*_gt) the solid is known to decompose. These items allow
               a range of temperatures to be given. 

               _chemical_temperature_decomposition should always be used in
               preference to these items whenever possible.
;

_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_decomposition_gt'
_related_function  alternate 
_related_item '_chemical_temperature_decomposition'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_contact_author_phone
_category 'audit_contact_author'
_definition
 
;
The telephone number of the author of the data block to whom
               correspondence should be addressed.

               The recommended style includes the international dialing
               prefix, the area code in parentheses, followed by the
               local number and any extension number prefixed by 'x',
               with no spaces.
;

_list  no 
_name '_audit_contact_author_phone'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   12(34)9477330 
   12()349477330 
   12(34)9477330x5543 

_space_group_name_Hall
_category 'space_group'
_definition
 
;
Space group symbol defined by Hall.

               Each component of the space group name is separated by a 
               space or an underscore.  The use of space is strongly
               recommended.  The underscore is only retained because it
               was used in earlier archived files.  It should not be 
               used in new CIFs. 

               _space_group_name_Hall uniquely defines the space group and
               its reference to a particular coordinate system.

               Ref: Hall, S. R. (1981). Acta Cryst. A37, 517-525
                    [See also International Tables for Crystallography,
                    Vol.B (1993) 1.4 Appendix B] 
;

_list  both 
_list_reference '_space_group_id'
_name '_space_group_name_Hall'
_related_function  alternate 
_related_item '_symmetry_space_group_name_Hall'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  'P 2c -2ac' 'equivalent to Pca21'
  '-I 4bd 2ab 3' 'equivalent to Ia3d'

_reflns_class_code
_category 'reflns_class'
_definition 'The code identifying a certain reflection class.'
_list  yes 
_list_link_child '_refln_class_code'
_name '_reflns_class_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   m1 
   s2 

_geom_torsion_atom_site_label_2
_category 'geom_torsion'
_definition
 
;
The labels of the four atom sites which define the torsion angle
               specified by _geom_torsion. These must match codes specified as
               _atom_site_label in the atom list. The torsion angle definition
               should be that of Klyne and Prelog. The vector direction
               *_label_2 to *_label_3 is the viewing direction, and the torsion
               angle is the angle of twist required to superimpose the
               projection of the vector site2-site1 onto the projection of the
               vector site3-site4. Clockwise torsions are positive,
               anticlockwise torsions are negative.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_torsion_atom_site_label_2'
_type  char 
_type_conditions  none 

_geom_contact_distance
_category 'geom_contact'
_definition 'The interatomic contact distance in angstroms.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_geom_contact_atom_site_label_'
_name '_geom_contact_distance'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_conform_dict_version
_category 'audit_conform'
_definition 'The version number of the conformant dictionary.'
_list  both 
_list_reference '_audit_conform_dict_name'
_name '_audit_conform_dict_version'
_type  char 
_type_conditions  none 

_chemical_conn_atom_NCA
_category 'chemical_conn_atom'
_definition 'The number of connected atoms excluding terminal hydrogen atoms.'
_enumeration_range  0: 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_NCA'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_crystal_density_method
_category 'exptl_crystal'
_definition 'The method used to measure _exptl_crystal_density_meas.'
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_method'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'flotation in aqueous KI'
  'not measured'
  'Berman density torsion balance'

_journal_language
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_language'
_type  char 
_type_conditions  none 

_exptl_absorpt_process_details
_category  exptl 
_definition
 
;
Description of the absorption process applied to the
               intensities. A literature reference should be supplied
               for psi-scan techniques.
;

_list  no 
_name '_exptl_absorpt_process_details'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Tompa analytical'
  'MolEN (Fair, 1990)'
  '(North, Phillips & Mathews, 1968)'

_diffrn_source_size
_category 'diffrn_source'
_definition 'The dimensions of the source as viewed from the sample.'
_list  no 
_name '_diffrn_source_size'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  '8mm x 0.4 mm fine-focus'
  'broad focus'

_journal_techeditor_notes
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_notes'
_type  char 
_type_conditions  none 

_exptl_crystal_size_max
_category 'exptl_crystal'
_definition
 
;
The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere then the *_rad item is
               its radius. If the crystal is a cylinder then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_size_max'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_index_l
_category 'diffrn_refln'
_definition
 
;
Miller indices of a measured reflection. These need not match
               the _refln_index_h, *_k, *_l values if a transformation of the
               original measured cell has taken place. Details of the cell
               transformation are described in _diffrn_reflns_reduction_process.
               See also _diffrn_reflns_transf_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_refln_index_l'
_type  numb 
_type_conditions  none 

_diffrn_refln_index_k
_category 'diffrn_refln'
_definition
 
;
Miller indices of a measured reflection. These need not match
               the _refln_index_h, *_k, *_l values if a transformation of the
               original measured cell has taken place. Details of the cell
               transformation are described in _diffrn_reflns_reduction_process.
               See also _diffrn_reflns_transf_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_refln_index_k'
_type  numb 
_type_conditions  none 

_diffrn_refln_index_h
_category 'diffrn_refln'
_definition
 
;
Miller indices of a measured reflection. These need not match
               the _refln_index_h, *_k, *_l values if a transformation of the
               original measured cell has taken place. Details of the cell
               transformation are described in _diffrn_reflns_reduction_process.
               See also _diffrn_reflns_transf_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_refln_index_h'
_type  numb 
_type_conditions  none 

_database_code_ICSD
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_ICSD'
_type  char 
_type_conditions  none 

_refine_ls_R_factor_obs
_category  refine 
_definition
 
;
Residual factor for the reflections classified as 'observed'
               (see _reflns_observed_criterion) and included in the
               refinement. The reflections also satisfy the resolution limits
               established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_R_factor_obs'
_related_function  replace 
_related_item '_refine_ls_R_factor_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_valence_param_ref_id
_category 'valence_param'
_definition
 
;
An identifier which links to the reference to the source
               from which the bond valence parameters are taken. A child
               of _valence_ref_id which it must match.
;

_list  yes 
_list_link_parent '_valence_ref_id'
_list_reference '_valence_param_id'
_name '_valence_param_ref_id'
_type  char 
_type_conditions  none 

_diffrn_source_type
_category 'diffrn_source'
_definition 'The make, model or name of the source of radiation.'
_list  no 
_name '_diffrn_source_type'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'NSLS beamline X8C'
  'Rigaku RU200'

_publ_section_figure_captions
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_figure_captions'
_type  char 
_type_conditions  none 

_refine_ls_class_R_I_factor
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the residual factor R(I) for the
               reflections judged significantly intense (i.e. satisfying the
               threshold specified by _reflns_threshold_expression) and
               included in the refinement.

               This is most often calculated in Rietveld refinements
               of powder data, where it is referred to as R~B~ or R~Bragg~

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the reflections of this class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_R_I_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_author_footnote
_category 'publ_author'
_definition
 
;
A footnote accompanying an author's name in the list of authors
               of a paper. Typically indicates sabbatical address, additional
               affiliations or date of decease.
;

_list  both 
_list_reference '_publ_author_name'
_name '_publ_author_footnote'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'On leave from U. Western Australia'
  'Also at Department of Biophysics'

_refln_refinement_status
_category  refln 
_definition 'Status of reflection in the structure refinement process.'
_enumeration_default  incl 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_refinement_status'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   incl  'included in ls process'
   excl  'excluded from ls process'
   extn  'excluded due to extinction'

_geom_hbond_site_symmetry_H
_category 'geom_hbond'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the hydrogen bond. These
               translations (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_site_symmetry_H'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_refine_ls_class_d_res_high
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the highest resolution in angstroms
               for the spacing in the reflections used in refinement. This is
               the lowest d value in a reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_d_res_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_author_ordinal
_category 'citation_author'
_definition
 
;
This data name defines the order of the author's name in the
               list of authors of a citation.
;

_list  yes 
_name '_citation_author_ordinal'
_type  char 
_type_conditions  none 

_exptl_crystals_number
_category  exptl 
_definition
 
;
The total number of crystals used in the measurement of
               intensities.
;

_enumeration_range  1: 
_list  no 
_name '_exptl_crystals_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_geom_hbond_site_symmetry_A
_category 'geom_hbond'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the hydrogen bond. These
               translations (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_site_symmetry_A'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_cell_length_c
_category  cell 
_definition
 
;
Unit-cell lengths in angstroms corresponding to the structure
               reported. The values of _refln_index_h, *_k, *_l must
               correspond to the cell defined by these values and _cell_angle_
               values. The values of _diffrn_refln_index_h, *_k, *_l may not
               correspond to these values if a cell transformation took place
               following the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_length_c'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_source_details
_category 'diffrn_source'
_definition 'A description of special aspects of the source used.'
_list  no 
_name '_diffrn_source_details'
_type  char 
_type_conditions  none 

_geom_hbond_site_symmetry_D
_category 'geom_hbond'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the hydrogen bond. These
               translations (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_site_symmetry_D'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_refine_ls_class_R_factor_all
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _refine_ls_class_wR_factor_all definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_R_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_type_scat_Cromer_Mann_b1
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_b1'
_type  numb 
_type_conditions  none 

_refine_ls_d_res_low
_category  refine 
_definition
 
;
The lowest resolution in angstroms for the interplanar spacing
               in the reflections used in refinement. This is the highest
               d value.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_d_res_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_meanI_over_sigI_obs
_category 'reflns_shell'
_definition
 
;
The ratio of the mean of the intensities of the reflections
               classified as 'observed' (see _reflns_observed_criterion) in
               this shell to the mean of the standard uncertainties of the
               intensities of the 'observed' reflections in the resolution
               shell.
;

_list  yes 
_name '_reflns_shell_meanI_over_sigI_obs'
_related_function  replace 
_related_item '_reflns_shell_meanI_over_sigI_gt'
_type  numb 
_type_conditions  none 

_publ_manuscript_incl_extra_info
_category 'publ_manuscript_incl'
_definition
 
;
A short note indicating the reason why the author wishes the
               corresponding data item marked for inclusion in the journal
               request list to be published.
;

_list  yes 
_list_reference '_publ_manuscript_incl_extra_item'
_name '_publ_manuscript_incl_extra_info'
_type  char 
_type_conditions  none 

_atom_type_description
_category 'atom_type'
_definition
 
;
A description of the atom(s) designated by this atom type. In
               most  cases this will be the element name and oxidation state of
               a single atom  species. For disordered or nonstoichiometric
               structures it will describe a combination of atom species.
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_description'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   deuterium 
   0.34Fe+0.66Ni 

_atom_type_scat_Cromer_Mann_b3
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_b3'
_type  numb 
_type_conditions  none 

_reflns_shell_Rmerge_F_all
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(F) for all reflections in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_F_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_crystal_F_000
_category 'exptl_crystal'
_definition
 
;
The effective number of electrons in the crystal unit cell
               contributing to F(000). It may contain dispersion contributions,
               and is calculated as

               F(000) = [ (sum f~r~)^2^ + (sum f~i~)^2^ ]^1/2^

               f~r~   = real part of the scattering factors at theta = 0
               f~i~   = imaginary part of the scattering factors at theta = 0

                        the sum is taken over each atom in the unit cell
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_F_000'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_percent_possible_gt
_category 'reflns_shell'
_definition
 
;
The percentage of geometrically possible reflections
               represented by significantly intense reflections
               (see _reflns_threshold_expression) measured for this
               resolution shell.
;

_enumeration_range  0.0:100.0 
_list  yes 
_name '_reflns_shell_percent_possible_gt'
_related_function  alternate 
_related_item '_reflns_shell_percent_possible_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   100.0   100.0 
   100.0   0.0 
   0.0   0.0 

_publ_section_comment
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_comment'
_type  char 
_type_conditions  none 

_publ_section_table_legends
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_table_legends'
_type  char 
_type_conditions  none 

_refine_ls_class_[]
_category 'category_overview'
_category.id 'refine_ls_class'
_definition
 
;
Data items in the REFINE_LS_CLASS category record details
               (for each reflection class separately) about the reflections
               used for the structure refinement.
;

_list  no 
_name '_refine_ls_class_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
        _refine_ls_class_R_factor_gt
        _refine_ls_class_code
                0.057    'Main'
                0.074    'Com'
                0.064    'NbRefls'
                0.046    'LaRefls'
                0.112    'Sat1'
                0.177    'Sat2'
;
  
;
Example 1 - example for a modulated structure extracted from van Smaalen
                [(1991). J. Phys.:Condens. Matter, 3, 1247-1263.]
;
 

_reflns_d_resolution_high
_category  reflns 
_definition
 
;
The highest and lowest resolution in angstroms for the
               interplanar spacings in the reflections. These are the
               smallest and largest d values.
;

_enumeration_range  0.0: 
_list  no 
_name '_reflns_d_resolution_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_date_accepted
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_accepted'
_type  char 
_type_conditions  none 

_journal_coeditor_phone
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_phone'
_type  char 
_type_conditions  none 

_chemical_conn_bond_atom_2
_category 'chemical_conn_bond'
_definition
 
;
Atom numbers which must match with chemical sequence numbers
               specified as _chemical_conn_atom_number values. These link the
               bond connection to the chemical numbering and atom sites.
;

_enumeration_range  1: 
_list  yes 
_list_link_parent '_chemical_conn_atom_number'
_name '_chemical_conn_bond_atom_2'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_chemical_conn_bond_atom_1
_category 'chemical_conn_bond'
_definition
 
;
Atom numbers which must match with chemical sequence numbers
               specified as _chemical_conn_atom_number values. These link the
               bond connection to the chemical numbering and atom sites.
;

_enumeration_range  1: 
_list  yes 
_list_link_parent '_chemical_conn_atom_number'
_name '_chemical_conn_bond_atom_1'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_atom_site_description
_category 'atom_site'
_definition
 
;
A description of special aspects of this site. See also
               _atom_site_refinement_flags.
;

_example 'Ag/Si disordered'
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_description'
_type  char 
_type_conditions  none 

_valence_param_id
_category 'valence_param'
_definition
 
;
An identifier for the valence parameters of a bond between
               the given atoms.
;

_list  yes 
_name '_valence_param_id'
_type  char 
_type_conditions  none 

_refine_ls_shift/su_mean_lt
_category  refine 
_definition
 
;
An upper limit for the average (ratio of the final
               least-squares parameter shift divided by the 
               final standard uncertainty).  This
               item is used when the average value of the shift divided by 
               the final standard uncertainty is too small to measure.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/su_mean_lt'
_related_function  alternate 
_related_item '_refine_ls_shift/su_mean'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_attenuator_code
_category 'diffrn_attenuator'
_definition
 
;
A code associated with a particular attenuator setting. This code
               is referenced by the _diffrn_refln_attenuator_code which is
               stored with the intensities. See _diffrn_attenuator_scale.
;

_list  yes 
_list_link_child '_diffrn_refln_attenuator_code'
_list_mandatory  yes 
_name '_diffrn_attenuator_code'
_type  char 
_type_conditions  none 

_database_code_MDF
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_MDF'
_type  char 
_type_conditions  none 

_diffrn_refln_detect_slit_vert
_category 'diffrn_refln'
_definition
 
;
Total slit apertures in degrees in the diffraction plane
               (*_horiz) and perpendicular to the diffraction plane (*_vert).
;

_enumeration_range  0.0:90.0 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_detect_slit_vert'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_diffrn_special_details
_category  diffrn 
_definition
 
;
Special details of the diffraction measurement process. Should
               include information about source instability, crystal motion,
               degradation and so on.
;

_example
 
;
The results may not be entirely reliable
               as the measurement was made during a heat
               wave when the air-conditioning had failed.
;

_list  no 
_name '_diffrn_special_details'
_type  char 
_type_conditions  none 

_audit_link_block_code
_category 'audit_link'
_definition
 
;
The value of _audit_block_code associated with a data block
               in the current file related to the current data block. The
               special value '.' may be used to refer to the current data
               block for completeness.
;

_list  yes 
_list_mandatory  yes 
_name '_audit_link_block_code'
_type  char 
_type_conditions  none 

_refine_ls_shift/esd_max
_category  refine 
_definition
 
;
The largest ratio of the final least-squares parameter
               shift divided by the final standard uncertainty (s.u.,
               formerly described as estimated standard deviation, e.s.d.).
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/esd_max'
_related_function  replace 
_related_item '_refine_ls_shift/su_max'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_computing_structure_refinement
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_structure_refinement'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_journal_year
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_year'
_type  char 
_type_conditions  none 

_exptl_crystal_density_meas_gt
_category 'exptl_crystal'
_definition
 
;
The value above which (*_gt) or below which (*_lt) the
               density measured using standard chemical and physical
               methods lies. The units are megagrams per cubic metre (grams per
               cubic centimetre).  These items should not be used to report
               new experimental work where _exptl_crystal_density_meas should
               be used.  They are intended for use in reporting information in
               existing databases and archives which would be misleading if
               reported under _exptl_crystal_density_meas.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas_gt'
_related_function  alternate 
_related_item '_exptl_crystal_density_meas'
_type  numb 
_type_conditions  none 
_units  Mg^-3^ 
_units_detail 'megagrams per cubic metre'

 loop_
   _example                                                                   
   _example_detail                                                            
  '_exptl_crystal_density_meas_lt  1.0' 'specimen floats in water'
  
;
_exptl_crystal_density_meas_gt    2.5   
                               _exptl_crystal_density_meas_lt    5.0
;
  
;
Only the range within which the density
                               lies was given in the original paper
;
 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_editor_[]
_category 'category_overview'
_category.id 'citation_editor'
_definition
 
;
Data items in the CITATION_EDITOR category record details
               about the editor associated with the book or book chapter
               citations in the _citation_ list.
;

_list  no 
_name '_citation_editor_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _citation_editor_citation_id
    _citation_editor_name
      5        'McKeever, B.M.'
      5        'Navia, M.A.'
      5        'Fitzgerald, P.M.D.'
      5        'Springer, J.P.'
;
  'Example 1 - hypothetical example.'

 loop_
   _category_mandatory.name                                                   
  '_citation_editor_citation_id'
  '_citation_editor_name'

_valence_param_[]
_category 'category_overview'
_category.id 'valence_param'
_definition
 
;
Data items in the VALENCE_PARAM category define the
               parameters used for calculating bond valences from bond
               lengths.  In addition to the parameters, a pointer
               is given to the reference (in VALENCE_REF) where the
               parameters have been published.
;

_list  no 
_name '_valence_param_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _valence_param_atom_1
    _valence_param_atom_1_valence
    _valence_param_atom_2
    _valence_param_atom_2_valence
    _valence_param_Ro
    _valence_param_B
    _valence_param_ref_id
    _valence_param_details
      Cu 2 O -2 1.679 0.37 a .
      Cu 2 O -2 1.649 0.37 j .
      Cu 2 N -3 1.64  0.37 m '2-coordinate N'
      Cu 2 N -3 1.76  0.37 m '3-coordinate N'
    loop_
    _valence_ref_id
    _valence_ref_reference 
      a  'Brown & Altermatt (1985), Acta Cryst. B41, 244-247'
      j  'Liu & Thorp (1993), Inorg. Chem. 32, 4102-4205'
      m  'See, Krause & Strub (1998), Inorg. Chem. 37, 5369-5375'
;
  'Example 1 - a bond valence parameter list with accompanying references.'

_exptl_crystal_density_meas_lt
_category 'exptl_crystal'
_definition
 
;
The value above which (*_gt) or below which (*_lt) the
               density measured using standard chemical and physical
               methods lies. The units are megagrams per cubic metre (grams per
               cubic centimetre).  These items should not be used to report
               new experimental work where _exptl_crystal_density_meas should
               be used.  They are intended for use in reporting information in
               existing databases and archives which would be misleading if
               reported under _exptl_crystal_density_meas.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas_lt'
_related_function  alternate 
_related_item '_exptl_crystal_density_meas'
_type  numb 
_type_conditions  none 
_units  Mg^-3^ 
_units_detail 'megagrams per cubic metre'

 loop_
   _example                                                                   
   _example_detail                                                            
  '_exptl_crystal_density_meas_lt  1.0' 'specimen floats in water'
  
;
_exptl_crystal_density_meas_gt    2.5   
                               _exptl_crystal_density_meas_lt    5.0
;
  
;
Only the range within which the density
                               lies was given in the original paper
;
 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_space_group_symop_id
_category 'space_group_symop'
_definition
 
;
An arbitrary identifier that uniquely labels each symmetry
               operation in the list.
;

_list  yes 
_list_mandatory  yes 
_name '_space_group_symop_id'
_related_function  alternate 
_related_item '_symmetry_equiv_pos_site_id'
_type  char 
_type_conditions  none 

_journal_coeditor_address
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_address'
_type  char 
_type_conditions  none 

_reflns_class_wR_factor_all
_category 'reflns_class'
_definition
 
;
For each reflection class, the weighted residual factors for all
               reflections and included in the refinement. The reflections also
               satisfy the resolution limits established by
               _reflns_class_d_res_high and _reflns_class_d_res_low.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the reflections of this class. See
               also _reflns_class_R_factor_ definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_wR_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_sites_solution_primary
_category 'atom_sites'
_definition
 
;
Codes which identify the methods used to locate the initial
               atomic sites. The *_primary code identifies how the first
               atom sites were determined; the *_secondary code identifies
               how the remaining non-hydrogen sites were located; and the
               *_hydrogens code identifies how the hydrogens were located.
;

_list  no 
_name '_atom_sites_solution_primary'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   difmap  'difference Fourier map'
   vecmap  'real-space vector search'
   heavy  'heavy-atom method'
   direct  'structure-invariant direct methods'
   geom  'inferred from neighbouring sites'
   disper  'anomalous-dispersion techniques'
   isomor  'isomorphous structure methods'

_atom_type_scat_length_neutron
_category 'atom_type'
_definition
 
;
The bound coherent scattering length in femtometres for the
               atom type at the isotopic composition used for the diffraction
               experiment.
;

_enumeration_default  0.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_length_neutron'
_type  numb 
_type_conditions  none 
_units  fm 
_units_detail  femtometres 

_diffrn_orient_matrix_UB_31
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_31'
_type  numb 
_type_conditions  none 

_refln_intensity_meas
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the intensity, in the measured units.
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_intensity_meas'
_type  numb 
_type_conditions  none 

_journal_coden_ASTM
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coden_ASTM'
_type  char 
_type_conditions  none 

_geom_hbond_distance_HA
_category 'geom_hbond'
_definition
 
;
Distances in angstroms between the donor and hydrogen (*_DH),
               hydrogen and acceptor (*_HA) and donor and acceptor (*_DA)
               sites in a hydrogen bond.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_distance_HA'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_extinction_method
_category  refine 
_definition
 
;
A description of the extinction correction method applied with
               the data item _refine_ls_extinction_coef. This description should
               include information about the correction method, either
               'Becker-Coppens' or 'Zachariasen'. The latter is sometimes
               referred to as the 'Larson' method even though it employs
               Zachariasen's formula.

               The Becker-Coppens procedure is referred to as 'type 1' when
               correcting secondary extinction dominated by the mosaic spread;
               as 'type 2' when secondary extinction is dominated by particle
               size and includes a primary extinction component; and as 'mixed'
               when there is a mixture of types 1 and 2.

               For the Becker-Coppens method it is also necessary to set the
               mosaic distribution as either 'Gaussian' or 'Lorentzian'; and
               the nature of the extinction as 'isotropic' or 'anisotropic'.
               Note that if either the 'mixed' or 'anisotropic' corrections
               are applied the multiple coefficients cannot be contained in
               *_extinction_coef and must be listed in _refine_special_details.

               Ref:  Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30,
                     129-153.
                     Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
                     Larson, A. C. (1967). Acta Cryst. 23, 664-665.
;

_enumeration_default  Zachariasen 
_list  no 
_name '_refine_ls_extinction_method'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'B-C type 2 Gaussian isotropic'
   none 

_journal_date_recd_electronic
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_recd_electronic'
_type  char 
_type_conditions  none 

_atom_sites_[]
_category 'category_overview'
_category.id 'atom_sites'
_definition
 
;
Data items in the ATOM_SITES category record details about
               the crystallographic cell and cell transformations, which are
               common to all atom sites.
;

_list  no 
_name '_atom_sites_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_atom_sites_Cartn_transform_axes
	  'c along z, astar along x, b along y'

    _atom_sites_Cartn_tran_matrix_11    58.39
    _atom_sites_Cartn_tran_matrix_12     0.00
    _atom_sites_Cartn_tran_matrix_13     0.00
    _atom_sites_Cartn_tran_matrix_21     0.00
    _atom_sites_Cartn_tran_matrix_22    86.70
    _atom_sites_Cartn_tran_matrix_23     0.00
    _atom_sites_Cartn_tran_matrix_31     0.00
    _atom_sites_Cartn_tran_matrix_32     0.00
    _atom_sites_Cartn_tran_matrix_33    46.27

;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

_diffrn_reflns_class_number
_category 'diffrn_reflns_class'
_definition
 
;
The total number of measured intensities for each reflection
               class, excluding the systematic absences arising from
               centring translations.
;

_enumeration_range  0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_contact_author_phone
_category  publ 
_definition
 
;
Telephone number of the author submitting the manuscript and
               data block.

               The recommended style includes the international dialing
               prefix, the area code in parentheses, followed by the
               local number and any extension number prefixed by 'x',
               with no spaces. The earlier convention of including
               the international dialing prefixes in parentheses is no longer
               recommended.
;

_list  no 
_name '_publ_contact_author_phone'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   12(34)9477330 
   12()349477330 
   12(34)9477330x5543 

_journal_coden_Cambridge
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coden_Cambridge'
_type  char 
_type_conditions  none 

_diffrn_refln_scan_rate
_category 'diffrn_refln'
_definition
 
;
The rate of scanning a reflection to measure the intensity in
               degrees per minute.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scan_rate'
_type  numb 
_type_conditions  none 
_units  deg/min 
_units_detail 'degrees per minute'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_absorpt_correction_type
_category  exptl 
_definition
 
;
The absorption correction type and method. The value 'empirical'
               should NOT be used unless no more detailed information is
               available.
;

_list  no 
_name '_exptl_absorpt_correction_type'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   analytical  'analytical from crystal shape'
   cylinder   cylindrical 
   empirical  'empirical from intensities'
   gaussian  'Gaussian from crystal shape'
   integration  'integration from crystal shape'
   multi-scan  'symmetry-related measurements'
   none  'no absorption correction applied'
   numerical  'numerical from crystal shape'
   psi-scan  'psi-scan corrections'
   refdelf  'refined from delta-F'
   sphere   spherical 

_diffrn_orient_matrix_UB_32
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_32'
_type  numb 
_type_conditions  none 

_cell_reciprocal_length_a
_category  cell 
_definition
 
;
The reciprocal cell lengths in inverse Angstroms.  These are 
               related to the real cell by the following equation:

               recip-a = b*c*sin(alpha)/V

               recip-b = c*a*sin(beta)/V

               recip-c = a*b*sin(gamma)/V

               where V is the cell volume.

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_reciprocal_length_a'
_type  numb 
_type_conditions  esd 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_cell_reciprocal_length_c
_category  cell 
_definition
 
;
The reciprocal cell lengths in inverse Angstroms.  These are 
               related to the real cell by the following equation:

               recip-a = b*c*sin(alpha)/V

               recip-b = c*a*sin(beta)/V

               recip-c = a*b*sin(gamma)/V

               where V is the cell volume.

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_reciprocal_length_c'
_type  numb 
_type_conditions  esd 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_class_number_total
_category 'reflns_class'
_definition
 
;
For each reflection class, the total number of reflections
               in the _refln_ list (not the _diffrn_refln_ list). It may
               include Friedel equivalent reflections (i.e. those which are
               symmetry equivalent under the Laue symmetry but inequivalent
               under the crystal class) according to the nature of the
               structure and the procedures used. The special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_number_total'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_d_spacing
_category  refln 
_definition
 
;
The d spacing in angstroms for this reflection. It is related
               to the (sin theta)/lambda value by the expression
                    _refln_d_spacing = 2/(_refln_sint/lambda)
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_d_spacing'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_coordinate_linkage
_category  citation 
_definition
 
;
_citation_coordinate_linkage states whether or not this citation
               is concerned with precisely the set of coordinates given in the
               data block. If, for instance, the publication described the same
               structure, but the coordinates had undergone further refinement
               prior to creation of the data block, the value of this data item
               would be 'no'.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_coordinate_linkage'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'citation unrelated to current coordinates'
   n  'abbreviation for "no"'
   yes  'citation related to current coordinates'
   y  'abbreviation for "yes"'

_publ_manuscript_creation
_category  publ 
_definition
 
;
A description of the wordprocessor package and computer used to
               create the word processed manuscript stored as
               _publ_manuscript_processed.
;

_example 'Tex file created by FrameMaker on a Sun 3/280'
_list  no 
_name '_publ_manuscript_creation'
_type  char 
_type_conditions  none 

_refln_F_squared_calc
_category  refln 
_definition
 
;
Calculated, measured and estimated standard uncertainty (derived
               from measurement) of the squared structure factors (in electrons
               squared for X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_squared_calc'
_type  numb 
_type_conditions  none 

_publ_contact_author_email
_category  publ 
_definition 'Email address in a form recognisable to international networks.'
_list  no 
_name '_publ_contact_author_email'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   name@host.domain.country 
   bm@iucr.org 

_reflns_shell_Rmerge_I_obs
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(I) for reflections classified as 'observed'
               (see _reflns_observed_criterion) in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_I_obs'
_related_function  replace 
_related_item '_reflns_shell_Rmerge_I_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_contact_author_name
_category 'audit_contact_author'
_definition
 
;
The name of the author of the data block to whom correspondence
               should be addressed.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

_list  no 
_name '_audit_contact_author_name'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Bleary, Percival R.'
  "O'Neil, F.K."
  'Van den Bossche, G.'
  'Yang, D.-L.'
  'Simonov, Yu.A'
  'M\"uller, H.A.'
  'Ross II, C.R.'

_refln_intensity_sigma
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the intensity, in the measured units.
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_intensity_sigma'
_type  numb 
_type_conditions  none 

_journal_techeditor_code
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_code'
_type  char 
_type_conditions  none 

_publ_author_name
_category 'publ_author'
_definition
 
;
The name of a publication author. If there are multiple authors
               they will be looped with _publ_author_address. The family
               name(s), followed by a comma and including any dynastic
               components, precedes the first names or initials.
;

_list  both 
_list_mandatory  yes 
_name '_publ_author_name'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Bleary, Percival R.'
  "O'Neil, F.K."
  'Van den Bossche, G.'
  'Yang, D.-L.'
  'Simonov, Yu.A'
  'M\"uller, H.A.'
  'Ross II, C.R.'

_atom_site_U_iso_or_equiv
_category 'atom_site'
_definition
 
;
Isotropic atomic displacement parameter, or equivalent isotropic
               atomic  displacement parameter, U(equiv), in angstroms squared,
               calculated from anisotropic atomic displacement  parameters.

               U(equiv) = (1/3) sum~i~[sum~j~(U^ij^ a*~i~ a*~j~ a~i~ a~j~)]

               a     = the real-space cell lengths
               a*    = the reciprocal-space cell lengths

               Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44,
                    775-776.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_U_iso_or_equiv'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_atom_site_U_equiv_geom_mean'
   conversion  '_atom_site_B_iso_or_equiv'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_percent_possible_obs
_category 'reflns_shell'
_definition
 
;
The percentage of geometrically possible reflections
               represented by reflections classified as 'observed'
               (see _reflns_observed_criterion) measured for this
               resolution shell.
;

_enumeration_range  0.0:100.0 
_list  yes 
_name '_reflns_shell_percent_possible_obs'
_related_function  replace 
_related_item '_reflns_shell_percent_possible_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   100.0   100.0 
   100.0   0.0 
   0.0   0.0 

_journal_index_type
_category 'journal_index'
_definition 'Indexing terms supplied by journals staff.'
_list  no 
_name '_journal_index_type'
_type  char 
_type_conditions  none 

_chemical_temperature_decomposition
_category  chemical 
_definition 'The temperature in kelvins at which a solid decomposes. '
_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_decomposition'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_shift/esd_mean
_category  refine 
_definition
 
;
The average ratio of the final least-squares parameter
               shift divided by the final standard uncertainty (s.u.,
               formerly described as estimated standard deviation, e.s.d.).
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/esd_mean'
_related_function  replace 
_related_item '_refine_ls_shift/su_mean'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_meanI_over_uI_all
_category 'reflns_shell'
_definition
 
;
The ratio of the mean of the intensities of all reflections
               in this shell to the mean of the standard uncertainties of the
               intensities of all reflections in the resolution shell.
;

_list  yes 
_name '_reflns_shell_meanI_over_uI_all'
_related_function  alternate 
_related_item '_reflns_shell_meanI_over_sigI_all'
_type  numb 
_type_conditions  none 

_reflns_shell_number_unique_obs
_category 'reflns_shell'
_definition
 
;
The total number of reflections classified as
               'observed' (see _reflns_observed_criterion) resulting from
               merging measured symmetry-equivalent reflections for this
               resolution shell.
;

_enumeration_range  0: 
_list  yes 
_name '_reflns_shell_number_unique_obs'
_related_function  replace 
_related_item '_reflns_shell_number_unique_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_index_subterm
_category 'journal_index'
_definition 'Indexing terms supplied by journals staff.'
_list  no 
_name '_journal_index_subterm'
_type  char 
_type_conditions  none 

_reflns_scale_[]
_category 'category_overview'
_category.id 'reflns_scale'
_definition
 
;
Data items in the REFLNS_SCALE category record details about
               the structure factor scales. They are referenced from within
               the REFLN list through _refln_scale_group_code.
;

_list  no 
_name '_reflns_scale_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _reflns_scale_group_code
    _reflns_scale_meas_F
      1  .895447

;
  
;
Example 1 - based on standard test data set p6122 of the Xtal distribution
                [Hall, King & Stewart (1995). Xtal3.4 User's Manual. Univ.
                Western Australia]
;
 

 loop_
   _category_mandatory.name                                                   
  '_reflns_scale_group_code'

_atom_sites_fract_tran_vector_1
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of Cartesian coordinates in the
               ATOM_SITES category to fractional  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_vector_1'
_type  numb 
_type_conditions  none 

_atom_sites_fract_tran_vector_2
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of Cartesian coordinates in the
               ATOM_SITES category to fractional  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_vector_2'
_type  numb 
_type_conditions  none 

_atom_sites_fract_tran_vector_3
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of Cartesian coordinates in the
               ATOM_SITES category to fractional  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_vector_3'
_type  numb 
_type_conditions  none 

_chemical_properties_physical
_category  chemical 
_definition 'A free description of the physical properties of the material.'
_list  no 
_name '_chemical_properties_physical'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   air-sensitive 
   moisture-sensitive 
   hygroscopic 
   deliquescent 
   oxygen-sensitive 
   photo-sensitive 
   pyrophoric 
   semiconductor 
  'ferromagnetic at low temperature'
  'paramagnetic and thermochromic'

_diffrn_orient_refln_index_k
_category 'diffrn_orient_refln'
_definition
 
;
The indices of a reflection used to define the orientation
               matrix. See _diffrn_orient_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_orient_refln_index_k'
_type  numb 
_type_conditions  none 

_diffrn_orient_refln_index_h
_category 'diffrn_orient_refln'
_definition
 
;
The indices of a reflection used to define the orientation
               matrix. See _diffrn_orient_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_orient_refln_index_h'
_type  numb 
_type_conditions  none 

_atom_sites_solution_hydrogens
_category 'atom_sites'
_definition
 
;
Codes which identify the methods used to locate the initial
               atomic sites. The *_primary code identifies how the first
               atom sites were determined; the *_secondary code identifies
               how the remaining non-hydrogen sites were located; and the
               *_hydrogens code identifies how the hydrogens were located.
;

_list  no 
_name '_atom_sites_solution_hydrogens'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   difmap  'difference Fourier map'
   vecmap  'real-space vector search'
   heavy  'heavy-atom method'
   direct  'structure-invariant direct methods'
   geom  'inferred from neighbouring sites'
   disper  'anomalous-dispersion techniques'
   isomor  'isomorphous structure methods'

_journal_coeditor_code
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_code'
_type  char 
_type_conditions  none 

_publ_contact_author
_category  publ 
_definition
 
;
The name and address of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff. It is preferable to use the separate data items
               _publ_contact_author_name and _publ_contact_author_address.
;

_list  no 
_name '_publ_contact_author'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  
;
Professor George Ferguson
                        Department of Chemistry and Biochemistry
                        University of Guelph
                        Ontario
                        Canada
                        N1G 2W1
;
 

_publ_author_[]
_category 'category_overview'
_category.id 'publ_author'
_definition
 
;
Data items in the PUBL_AUTHOR category record details of
               the authors of a manuscript submitted for publication.
;

_list  no 
_name '_publ_author_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _publ_author_name
    _publ_author_address

         'Willis, Anthony C.'
    ;    Research School of Chemistry
         Australian National University
         GPO Box 4
         Canberra, ACT
         Australia    2601
    ;
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_publ_author_name'

_refine_special_details
_category  refine 
_definition 'Description of special aspects of the refinement process.'
_list  no 
_name '_refine_special_details'
_type  char 
_type_conditions  none 

_diffrn_refln_angle_chi
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_chi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_publ_section_abstract
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_abstract'
_type  char 
_type_conditions  none 

_cell_formula_units_Z
_category  cell 
_definition
 
;
The number of the formula units in the unit cell as specified
               by _chemical_formula_structural, _chemical_formula_moiety or
               _chemical_formula_sum.
;

_enumeration_range  1: 
_list  no 
_name '_cell_formula_units_Z'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_exptl_crystal_density_meas_temp_gt
_category 'exptl_crystal'
_definition
 
;
Temperature in kelvins above which (*_gt) or below which
               (*_lt) _exptl_crystal_density_meas was determined. These
               items should not be used for reporting new work where the
               correct temperature of measurement should be given. They are
               intended for use in reporting information stored in databases
               or archives which would be misleading if reported under
               _exptl_crystal_density_meas_temp.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas_temp_gt'
_related_function  alternate 
_related_item '_exptl_crystal_density_meas_temp'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _example                                                                   
   _example_detail                                                            
  '_exptl_crystal_density_meas_temp_lt   300' 
;
The density was measured at some unspecified
                                temperature below room temperature.
;
 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_transf_matrix_22
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_22'
_type  numb 
_type_conditions  none 

_diffrn_reflns_transf_matrix_23
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_23'
_type  numb 
_type_conditions  none 

_diffrn_reflns_transf_matrix_21
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_21'
_type  numb 
_type_conditions  none 

_refln_observed_status
_category  refln 
_definition
 
;
Classification of a reflection so as to indicate its status with
               respect to inclusion in refinement and calculation of R factors.
;

_enumeration_default  o 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_observed_status'
_related_function  replace 
_related_item '_refln_include_status'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   o  
;
satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      observed by _reflns_observed_criterion
;
 
   <  
;
satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      unobserved by _reflns_observed_criterion
;
 
   -  'systematically absent reflection'
   x  'unreliable measurement -- not used'
   h  'does not satisfy _refine_ls_d_res_high'
   l  'does not satisfy _refine_ls_d_res_low'

_publ_section_discussion
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_discussion'
_type  char 
_type_conditions  none 

_diffrn_standards_[]
_category 'category_overview'
_category.id 'diffrn_standards'
_definition
 
;
Data items in the DIFFRN_STANDARDS category record details
               about the set of standard reflections used to monitor intensity
               stability during measurement of diffraction intensities.

               Note that these records describe properties common to the set of
               standard reflections, not the standard reflections themselves.
;

_list  no 
_name '_diffrn_standards_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_standards_number            3
    _diffrn_standards_interval_time     120
    _diffrn_standards_decay_%           0
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_atom_sites_Cartn_tran_vector_1
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of fractional coordinates in the
               ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_vector_1'
_type  numb 
_type_conditions  none 

_atom_sites_Cartn_tran_vector_2
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of fractional coordinates in the
               ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_vector_2'
_type  numb 
_type_conditions  none 

_atom_sites_Cartn_tran_vector_3
_category 'atom_sites'
_definition
 
;
Elements of a 3 x 1 translation vector used in the
               transformation of fractional coordinates in the
               ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_vector_3'
_type  numb 
_type_conditions  none 

_refine_ls_R_Fsqd_factor
_category  refine 
_definition
 
;
Residual factor R(Fsqd), calculated on the squared amplitudes
               of the observed and calculated structure factors, for
               significantly intense reflections (satisfying
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _refine_ls_d_res_high and _refine_ls_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_R_Fsqd_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_code_NBS
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_NBS'
_type  char 
_type_conditions  none 

_refine_diff_density_rms
_category  refine 
_definition
 
;
The largest, smallest and root-mean-square-deviation, in
               electrons per angstrom cubed, of the final difference electron
               density. The *_rms value is measured with
               respect to the arithmetic mean density, and is derived from
               summations over each grid point in the asymmetric unit of
               the cell. This quantity is useful for assessing the
               significance of *_min and *_max values, and also for
               defining suitable contour levels.
;

_list  no 
_name '_refine_diff_density_rms'
_type  numb 
_type_conditions  esd 
_units 'e_A^-3^'
_units_detail 'electrons per cubic angstrom'

_citation_id
_category  citation 
_definition
 
;
The value of _citation_id must uniquely identify a record in the
               _citation_ list.

               The _citation_id 'primary' should be used to indicate the
               citation that the author(s) consider to be the most pertinent to
               the contents of the data block.

               Note that this item need not be a number;  it can be any unique
               identifier.
;

_list  yes 
_list_mandatory  yes 
_name '_citation_id'
_type  char 
_type_conditions  none 

 loop_
   _list_link_child                                                           
  '_citation_author_citation_id'
  '_citation_editor_citation_id'

 loop_
   _example                                                                   
   primary 
   1 
   2 
   3 

_atom_site_aniso_U_11
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_11'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_atom_site_aniso_U_12
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_12'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_atom_site_aniso_U_13
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_13'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_reflns_limit_k_min
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_k_min'
_type  numb 
_type_conditions  none 

_geom_bond_publ_flag
_category 'geom_bond'
_definition
 
;
This code signals if the bond distance is referred to in a
               publication or should be placed in a list of significant bond
               distances.
;

_enumeration_default  no 
_list  yes 
_list_reference '_geom_bond_atom_site_label_'
_name '_geom_bond_publ_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'do not include bond in special list'
   n  'abbreviation for "no"'
   yes  'do include bond in special list'
   y  'abbreviation for "yes"'

_diffrn_measurement_specimen_support
_category 'diffrn_measurement'
_definition
 
;
The physical device used to support the crystal during data
               collection.
;

_list  no 
_name '_diffrn_measurement_specimen_support'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'glass capillary'
  'quartz capillary'
   fiber 
  'metal loop'

_refine_ls_number_parameters
_category  refine 
_definition
 
;
The number of parameters refined in the least-squares process.
               If possible this number should include some contribution from
               the restrained parameters. The restrained parameters are
               distinct from the constrained parameters (where one or more
               parameters are linearly dependent on the refined value of
               another). Least-squares restraints often depend on geometry or
               energy considerations and this makes their direct contribution
               to this number, and to the goodness-of-fit calculation,
               difficult to assess.
;

_enumeration_range  0: 
_list  no 
_name '_refine_ls_number_parameters'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_valence_param_details
_category 'valence_param'
_definition 'Details or comments on the bond valence parameters.'
_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_details'
_type  char 
_type_conditions  none 

_reflns_class_[]
_category 'category_overview'
_category.id 'reflns_class'
_definition
 
;
Data items in the REFLNS_CLASS category record details, for
               each reflection class, about the reflections used to determine
               the structural parameters.
;

_list  no 
_name '_reflns_class_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
        _reflns_class_number_gt
        _reflns_class_code
               584     'Main'
               226     'Sat1'
               50      'Sat2'
;
  
;
Example 1 - example corresponding to the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~.
;
 

_geom_hbond_distance_DA
_category 'geom_hbond'
_definition
 
;
Distances in angstroms between the donor and hydrogen (*_DH),
               hydrogen and acceptor (*_HA) and donor and acceptor (*_DA)
               sites in a hydrogen bond.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_distance_DA'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_crystal_face_perp_dist
_category 'exptl_crystal_face'
_definition
 
;
The perpendicular distance in millimetres of the face to the
               centre of rotation of the crystal.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_exptl_crystal_face_index_'
_name '_exptl_crystal_face_perp_dist'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_conform_dict_location
_category 'audit_conform'
_definition
 
;
A file name or uniform resource locator (URL) where the
               conformant dictionary resides.
;

_list  both 
_list_reference '_audit_conform_dict_name'
_name '_audit_conform_dict_location'
_type  char 
_type_conditions  none 

_geom_angle_atom_site_label_2
_category 'geom_angle'
_definition
 
;
The labels of the three atom sites which define the angle
               specified by _geom_angle. These must match labels specified as
               _atom_site_label in the atom list. Label 2 identifies the site at
               the apex of the angle.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_angle_atom_site_label_2'
_type  char 
_type_conditions  none 

_geom_angle_atom_site_label_3
_category 'geom_angle'
_definition
 
;
The labels of the three atom sites which define the angle
               specified by _geom_angle. These must match labels specified as
               _atom_site_label in the atom list. Label 2 identifies the site at
               the apex of the angle.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_angle_atom_site_label_3'
_type  char 
_type_conditions  none 

_geom_angle_atom_site_label_1
_category 'geom_angle'
_definition
 
;
The labels of the three atom sites which define the angle
               specified by _geom_angle. These must match labels specified as
               _atom_site_label in the atom list. Label 2 identifies the site at
               the apex of the angle.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_angle_atom_site_label_1'
_type  char 
_type_conditions  none 

_exptl_crystal_face_index_h
_category 'exptl_crystal_face'
_definition
 
;
Miller indices of the crystal face associated with the value
               _exptl_crystal_face_perp_dist.
;

_list  yes 
_list_mandatory  yes 
_name '_exptl_crystal_face_index_h'
_type  numb 
_type_conditions  none 

_atom_site_refinement_flags_occupancy
_category 'atom_site'
_definition
 
;
A code which indicates that refinement restraints or
               constraints were applied to the occupancy of this site.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_refinement_flags_occupancy'
_related_function  alternate 
_related_item '_atom_site_refinement_flags_posn'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   .  'no constraints on site occupancy parameters'
   P  'site occupancy constraint'

_chemical_conn_atom_[]
_category 'category_overview'
_category.id 'chemical_conn_atom'
_definition
 
;
Data items in the _chemical_conn_atom_ and _chemical_conn_bond_
               categories record details about the 2D chemical structure of
               the molecular species. They allow a 2D chemical diagram to be
               reconstructed for use in a publication or in a database search
               for structural and substructural relationships.

               The _chemical_conn_atom_ data items provide information about the
               chemical properties of the atoms in the structure. In cases
               where crystallographic and molecular symmetry elements coincide
               they must also contain symmetry-generated atoms, so that the
               _chemical_conn_atom_ and _chemical_conn_bond_ data items will
               always describe a complete chemical entity.
;

_list  no 
_name '_chemical_conn_atom_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _chemical_conn_atom_number
    _chemical_conn_atom_type_symbol
    _chemical_conn_atom_display_x
    _chemical_conn_atom_display_y
    _chemical_conn_atom_NCA
    _chemical_conn_atom_NH
        1   S    .39  .81   1   0
        2   S    .39  .96   2   0
        3   N    .14  .88   3   0
        4   C    .33  .88   3   0
        5   C    .11  .96   2   2
        6   C    .03  .96   2   2
        7   C    .03  .80   2   2
        8   C    .11  .80   2   2
        9   S    .54  .81   1   0
        10  S    .54  .96   2   0
        11  N    .80  .88   3   0
        12  C    .60  .88   3   0
        13  C    .84  .96   2   2
        14  C    .91  .96   2   2
        15  C    .91  .80   2   2
        16  C    .84  .80   2   2
;
  
;
Example 1 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [(1996). Acta Cryst. C52, 951-953].
;
 

 loop_
   _category_mandatory.name                                                   
  '_chemical_conn_atom_type_symbol'

_journal_coeditor_name
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_name'
_type  char 
_type_conditions  none 

_symmetry_space_group_name_H-M
_category  symmetry 
_definition
 
;
Hermann-Mauguin space-group symbol. Note that the H-M symbol does
              not necessarily contain complete information about the symmetry
              and the space-group origin. If used always supply the FULL symbol
              from International Tables for Crystallography, Vol. A (1987) and
              indicate the origin and the setting if it is not implicit. If
              there is any doubt that the equivalent positions can be uniquely
              deduced from this symbol specify the _symmetry_equiv_pos_as_xyz
              or *_Hall data items as well. Leave spaces between symbols
              referring to different axes.
;

_list  no 
_name '_symmetry_space_group_name_H-M'
_related_function  replace 
_related_item '_space_group_name_H-M_alt'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'P 1 21/m 1'
  'P 2/n 2/n 2/n (origin at -1)'
  'R -3 2/m'

_reflns_limit_h_max
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_h_max'
_type  numb 
_type_conditions  none 

_publ_author_address
_category 'publ_author'
_definition
 
;
The address of a publication author. If there is more than one
               author this will be looped with _publ_author_name.
;

_example
 
;
Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;

_list  both 
_list_reference '_publ_author_name'
_name '_publ_author_address'
_type  char 
_type_conditions  none 

_diffrn_standards_interval_count
_category 'diffrn_standards'
_definition
 
;
The number of reflection intensities, or the time in minutes,
               between the measurement of standard reflection intensities.
;

_enumeration_range  0: 
_list  no 
_name '_diffrn_standards_interval_count'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_source_current
_category 'diffrn_source'
_definition
 
;
The current in milliamperes at which the radiation source was
               operated.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_source_current'
_type  numb 
_type_conditions  none 
_units  mA 
_units_detail  milliamperes 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_techeditor_phone
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_phone'
_type  char 
_type_conditions  none 

_exptl_crystal_density_meas
_category 'exptl_crystal'
_definition
 
;
Density values measured using standard chemical and physical
               methods. The units are megagrams per cubic metre (grams per
               cubic centimetre).
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas'
_type  numb 
_type_conditions  esd 
_units  Mgm^-3^ 
_units_detail 'megagrams per cubic metre'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_author_name
_category 'audit_author'
_definition
 
;
The name of an author of this data block. If there are multiple
               authors, _audit_author_name is looped with _audit_author_address.
               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

_list  yes 
_list_mandatory  yes 
_name '_audit_author_name'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Bleary, Percival R.'
  "O'Neil, F.K."
  'Van den Bossche, G.'
  'Yang, D.-L.'
  'Simonov, Yu.A'
  'M\"uller, H.A.'
  'Ross II, C.R.'

_atom_site_label_component_3
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_3'
_type  char 
_type_conditions  none 

_space_group_IT_number
_category 'space_group'
_definition
 
;
The number as assigned in International Tables for
               Crystallography Vol A, specifying the proper affine class (i.e.
               the orientation preserving affine class) of space groups
               (crystallographic space group type) to which the space group
               belongs.  This number defines the space group type but not
               the coordinate system in which it is expressed.
;

_enumeration_range  1:230 
_list  both 
_list_reference '_space_group_id'
_name '_space_group_IT_number'
_related_function  alternate 
_related_item '_symmetry_Int_Tables_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   230.0   230.0 
   230.0   1.0 
   1.0   1.0 

_computing_molecular_graphics
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_molecular_graphics'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_reflns_class_d_res_low
_category 'reflns_class'
_definition
 
;
For each reflection class the lowest resolution in angstroms
               for the interplanar spacing in the reflections used in
               refinement. This is the largest d value.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_d_res_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_requested_coeditor_name
_category  publ 
_definition
 
;
The name of the Co-editor whom the authors would like to
               process the submitted manuscript.
;

_list  no 
_name '_publ_requested_coeditor_name'
_type  char 
_type_conditions  none 

_exptl_[]
_category 'category_overview'
_category.id  exptl 
_definition
 
;
Data items in the EXPTL category record details about the
               experimental work prior to the intensity measurement, and
               about the absorption correction technique employed.
;

_list  no 
_name '_exptl_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_exptl_absorpt_coefficient_mu     0.962
    _exptl_absorpt_correction_type    psi-scan
    _exptl_absorpt_process_details   'North, Phillips & Mathews (1968)'
    _exptl_absorpt_correction_T_min   0.929
    _exptl_absorpt_correction_T_max   0.997
;
  
;
Example 1 - based on a paper by Steiner [(1996). Acta Cryst. C52,
                2554-2556].
;
 

_cell_measurement_wavelength
_category  cell 
_definition
 
;
The wavelength in angstroms of the radiation used to measure
               the unit cell. If this is not specified, the wavelength is
               assumed to be the same as that given in
               _diffrn_radiation_wavelength.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_measurement_wavelength'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_limit_l_max
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_l_max'
_type  numb 
_type_conditions  none 

_diffrn_orient_matrix_UB_21
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_21'
_type  numb 
_type_conditions  none 

_reflns_Friedel_coverage
_category  reflns 
_definition
 
;
The proportion of Friedel related reflections present in
               the number of the 'independent reflections' specified by
               the item _reflns_number_total.

               This proportion is calculated as the ratio:

                 [N(Crystal class) - N(Laue symmetry)] / N(Laue symmetry)

               where, working from the _diffrn_refln_ list,

               N(Crystal class) is the number of reflections obtained on
                  averaging under the symmetry of the crystal class
               N(Laue symmetry) is the number of reflections obtained on
                  averaging under the Laue symmetry.

               Examples:
                 (a) For centrosymmetric structures its value is
                     necessarily equal to 0.0 as the crystal class
                     is identical to the Laue symmetry.
                 (b) For whole-sphere data for a crystal in the space
                     group P1, _reflns_Friedel_coverage is equal to 1.0,
                     as no reflection h k l is equivalent to -h -k -l
                     in the crystal class and all Friedel pairs
                     {h k l; -h -k -l} have been measured.
                 (c) For whole-sphere data in space group Pmm2, the value
                     will be < 1.0 because although reflections h k l and
                     -h -k -l are not equivalent when h k l indices are
                     non-zero, they are when l=0.
                 (d) For a crystal in the group Pmm2 measurements of the
                     two inequivalent octants h >= 0, k >=0, l lead to the
                     same value as in (c), whereas measurements of the
                     two equivalent octants h >= 0, k, l >= 0 will lead to
                     a zero value for _reflns_Friedel_coverage.
;

_enumeration_range  0.0:1.0 
_list  no 
_name '_reflns_Friedel_coverage'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_diffrn_reflns_limit_h_max
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_h_max'
_type  numb 
_type_conditions  none 

_diffrn_radiation_inhomogeneity
_category 'diffrn_radiation'
_definition
 
;
Half-width in millimetres of the incident beam in the
               direction perpendicular to the diffraction plane.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_radiation_inhomogeneity'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_standards_scale_sigma
_category 'diffrn_standards'
_definition
 
;
The standard uncertainty (e.s.d.) of the individual mean
               standard scales applied to the intensity data.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_standards_scale_sigma'
_related_function  replace 
_related_item '_diffrn_standards_scale_u'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_database_id_Medline
_category  citation 
_definition
 
;
Accession number used by Medline to categorize a specific
               bibliographic entry.
;

_enumeration_range  1: 
_example  89064067 
_list  yes 
_list_reference '_citation_id'
_name '_citation_database_id_Medline'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_citation_page_last
_category  citation 
_definition
 
;
The first and last pages of the citation;  relevant for both
               journal articles and book chapters.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_page_last'
_type  char 
_type_conditions  none 

_diffrn_crystal_treatment
_category  diffrn 
_definition
 
;
Remarks about how the crystal was treated prior to intensity
               measurement. Particularly relevant when intensities were
               measured at low temperature.
;

_list  no 
_name '_diffrn_crystal_treatment'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'equilibrated in hutch for 24 hours'
  'flash frozen in liquid nitrogen'
  'slow cooled with direct air stream'

_chemical_name_mineral
_category  chemical 
_definition
 
;
Mineral name accepted by the International Mineralogical
               Association. Use only for natural minerals. See also
               _chemical_compound_source.
;

_example  chalcopyrite 
_list  no 
_name '_chemical_name_mineral'
_type  char 
_type_conditions  none 

_diffrn_reflns_class_description
_category 'diffrn_reflns_class'
_definition 'Description of each reflection class.'
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_description'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'm=1 first order satellites'
  'H0L0 common projection reflections'

_diffrn_radiation_collimation
_category 'diffrn_radiation'
_definition 'The collimation or focusing applied to the radiation.'
_list  no 
_name '_diffrn_radiation_collimation'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  '0.3 mm double-pinhole'
  '0.5 mm'
  'focusing mirrors'

_chemical_formula_structural
_category 'chemical_formula'
_definition
 
;
See _chemical_formula_[] for the rules for writing chemical
               formulae for inorganics, organometallics, metal complexes etc.,
               in which  bonded groups are preserved as discrete entities within
               parentheses, with post-multipliers as required. The order of the
               elements should give as much information as possible about the
               chemical structure. Parentheses may be  used and nested as
               required. This formula should correspond to the structure as
               actually reported, i.e. trace elements not included in atom type
               and atom site lists should not be included in this formula (see
               also _chemical_formula_analytical).
;

_list  no 
_name '_chemical_formula_structural'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Ca ((Cl O3)2 O)2 (H2 O)6'
  '(Pt (N H3)2 (C5 H7 N3 O)2) (Cl O4)2'

_publ_body_contents
_category 'publ_body'
_definition 'A text section of a submitted paper.'
_list  yes 
_list_reference '_publ_body_label'
_name '_publ_body_contents'
_type  char 
_type_conditions  none 

_diffrn_measurement_device_type
_category 'diffrn_measurement'
_definition
 
;
The make, model or name of the measurement device
               (goniometer) used.
;

_list  no 
_name '_diffrn_measurement_device_type'
_type  char 
_type_conditions  none 

_chemical_formula_analytical
_category 'chemical_formula'
_definition
 
;
Formula determined by standard chemical analysis including trace
               elements. See _chemical_formula_[] for rules for writing chemical
               formulae. Parentheses are used only for standard uncertainties
               (e.s.d.'s).
;

_example 'Fe2.45(2)  Ni1.60(3)  S4'
_list  no 
_name '_chemical_formula_analytical'
_type  char 
_type_conditions  none 

_citation_database_id_CSD
_category  citation 
_definition
 
;
Identifier ('refcode') of the database record in the Cambridge
            Structural Database containing details of the cited structure.
;

_example  LEKKUH 
_list  yes 
_list_reference '_citation_id'
_name '_citation_database_id_CSD'
_type  char 
_type_conditions  none 

_symmetry_cell_setting
_category  symmetry 
_definition 'The cell settings for this space-group symmetry.'
_list  no 
_name '_symmetry_cell_setting'
_related_function  replace 
_related_item '_space_group_crystal_system'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   triclinic 
   monoclinic 
   orthorhombic 
   tetragonal 
   rhombohedral 
   trigonal 
   hexagonal 
   cubic 

_diffrn_standard_refln_index_h
_category 'diffrn_standard_refln'
_definition
 
;
Miller indices of standard reflections used in the diffraction
               measurement process.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_standard_refln_index_h'
_type  numb 
_type_conditions  none 

_diffrn_standard_refln_index_k
_category 'diffrn_standard_refln'
_definition
 
;
Miller indices of standard reflections used in the diffraction
               measurement process.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_standard_refln_index_k'
_type  numb 
_type_conditions  none 

_diffrn_standard_refln_index_l
_category 'diffrn_standard_refln'
_definition
 
;
Miller indices of standard reflections used in the diffraction
               measurement process.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_standard_refln_index_l'
_type  numb 
_type_conditions  none 

_refine_ls_R_I_factor
_category  refine 
_definition
 
;
Residual factor R(I) for significantly intense reflections
               (satisfying _reflns_threshold_expression) and included in
               the refinement.

               This is most often calculated in Rietveld refinements of powder
               data, where it is referred to as R~B~ or R~Bragg~.

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_R_I_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_coeditor_email
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_email'
_type  char 
_type_conditions  none 

_geom_bond_valence
_category 'geom_bond'
_definition 'The bond valence calculated from _geom_bond_distance '
_list  yes 
_list_reference '_geom_bond_atom_site_label_'
_name '_geom_bond_valence'
_type  numb 
_type_conditions  none 

_citation_abstract
_category  citation 
_definition
 
;
Abstract for the citation. This is used most when the
               citation is extracted from a bibliographic database that
               contains full text or abstract information.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_abstract'
_type  char 
_type_conditions  none 

_chemical_compound_source
_category  chemical 
_definition
 
;
Description of the source of the compound under study, or of the
               parent  molecule if a simple derivative is studied. This includes
               the place of  discovery for minerals or the actual source of a
               natural product.
;

_list  no 
_name '_chemical_compound_source'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'From Norilsk (USSR)'
  'Extracted from the bark of Cinchona Naturalis'

_refln_index_l
_category  refln 
_definition
 
;
Miller indices of the reflection. The values of the Miller
               indices in the REFLN category must correspond to the cell
               defined by cell lengths and cell angles in the CELL category.
;

_list  yes 
_list_mandatory  yes 
_name '_refln_index_l'
_type  numb 
_type_conditions  none 

_geom_angle
_category 'geom_angle'
_definition
 
;
Angle in degrees defined by the three sites
               _geom_angle_atom_site_label_1, *_2 and *_3. Site at *_2
               is at the apex of the angle.
;

_list  yes 
_list_reference '_geom_angle_atom_site_label_'
_name '_geom_angle'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

_refln_index_k
_category  refln 
_definition
 
;
Miller indices of the reflection. The values of the Miller
               indices in the REFLN category must correspond to the cell
               defined by cell lengths and cell angles in the CELL category.
;

_list  yes 
_list_mandatory  yes 
_name '_refln_index_k'
_type  numb 
_type_conditions  none 

_refln_index_h
_category  refln 
_definition
 
;
Miller indices of the reflection. The values of the Miller
               indices in the REFLN category must correspond to the cell
               defined by cell lengths and cell angles in the CELL category.
;

_list  yes 
_list_mandatory  yes 
_name '_refln_index_h'
_type  numb 
_type_conditions  none 

_diffrn_attenuator_scale
_category 'diffrn_attenuator'
_definition
 
;
The scale factor applied when an intensity measurement is
                reduced by an attenuator identified by _diffrn_attenuator_code.
                This scale must be multiplied by the measured intensity to
                convert it to the same scale as unattenuated intensities.
;

_enumeration_range  1.0: 
_list  yes 
_list_reference '_diffrn_attenuator_code'
_name '_diffrn_attenuator_scale'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_publ_manuscript_text
_category  publ 
_definition
 
;
The full manuscript of a paper (excluding figures and possibly
               the tables) output as standard ASCII text.
;

_list  no 
_name '_publ_manuscript_text'
_type  char 
_type_conditions  none 

_chemical_melting_point_gt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above
               which (*_gt) the melting point, the temperature at which a
               crystalline solid changes to a liquid, lies. These items allow a
               range of temperatures to be given.

               _chemical_melting_point should always be used in preference
               to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_chemical_melting_point_gt'
_related_function  alternate 
_related_item '_chemical_melting_point'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_space_group_id
_category 'space_group'
_definition 'This is an identifier needed if _space_group_ items are looped.'
_list  yes 
_list_link_child '_space_group_symop_sg_id'
_list_mandatory  yes 
_name '_space_group_id'
_type  char 
_type_conditions  none 

_cell_angle_alpha
_category  cell 
_definition
 
;
Unit-cell angles in degrees of the reported structure.
               The values of _refln_index_h, *_k, *_l must correspond to the
               cell defined by these values and _cell_length_a, *_b and *_c.
               The values of _diffrn_refln_index_h, *_k, *_l may not correspond
               to these values if a cell transformation took place following
               the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_angle_alpha'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_publ_section_synopsis
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_synopsis'
_type  char 
_type_conditions  none 

_diffrn_radiation_[]
_category 'category_overview'
_category.id 'diffrn_radiation'
_definition
 
;
Data items in the DIFFRN_RADIATION category describe the
               radiation used in measuring diffraction intensities, its
               collimation and monochromatisation before the sample.

               Post-sample treatment of the beam is described by data items
               in the DIFFRN_DETECTOR category.
;

_list  no 
_name '_diffrn_radiation_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_radiation_type             'Cu K\a'
    _diffrn_radiation_monochromator    'graphite'
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_chemical_temperature_sublimation_lt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above which
              (*_gt) the solid is known to sublime. These items allow a
              range of temperatures to be given. 

              _chemical_temperature_sublimation should always be used in
              preference to these items whenever possible.
;

_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_sublimation_lt'
_related_function  alternate 
_related_item '_chemical_temperature_sublimation'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_class_R_Fsqd_factor
_category 'reflns_class'
_definition
 
;
For each reflection class, the residual factor R(F^2^) calculated
               on the squared amplitudes of the observed and calculated
               structure factors, for the reflections judged significantly
               intense (i.e. satisfying the threshold specified by
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _reflns_class_d_res_high and _reflns_class_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the reflections of this class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_R_Fsqd_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_scale_group_code
_category  refln 
_definition
 
;
Code identifying the structure-factor scale. This code must
               correspond to one of the _reflns_scale_group_code values.
;

_list  yes 
_list_link_parent '_reflns_scale_group_code'
_list_reference '_refln_index_'
_name '_refln_scale_group_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   2 
   3 
   s1 
   A 
   B 
   c1 
   c2 
   c3 

_atom_type_scat_Cromer_Mann_a1
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_a1'
_type  numb 
_type_conditions  none 

_exptl_crystal_size_length
_category 'exptl_crystal'
_definition
 
;
The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere then the *_rad item is
               its radius. If the crystal is a cylinder then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_size_length'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_cell_angle_gamma
_category  cell 
_definition
 
;
Unit-cell angles in degrees of the reported structure.
               The values of _refln_index_h, *_k, *_l must correspond to the
               cell defined by these values and _cell_length_a, *_b and *_c.
               The values of _diffrn_refln_index_h, *_k, *_l may not correspond
               to these values if a cell transformation took place following
               the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_angle_gamma'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_atom_type_oxidation_number
_category 'atom_type'
_definition 'Formal oxidation state of this atom type in the structure.'
_enumeration_default  0 
_enumeration_range  -8:8 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_oxidation_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   8.0   8.0 
   8.0   -8.0 
   -8.0   -8.0 

_diffrn_reflns_class_[]
_category 'category_overview'
_category.id 'diffrn_reflns_class'
_definition
 
;
Data items in the DIFFRN_REFLNS_CLASS category record details
               about the classes of reflections measured in the diffraction
               experiment.
;

_list  no 
_name '_diffrn_reflns_class_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
        _diffrn_reflns_class_number
        _diffrn_reflns_class_d_res_high
        _diffrn_reflns_class_d_res_low
        _diffrn_reflns_class_av_R_eq
        _diffrn_reflns_class_code
        _diffrn_reflns_class_description
               1580 0.551 6.136 0.015 'Main' 'm=0; main reflections'
               1045 0.551 6.136 0.010 'Sat1' 'm=1; first-order satellites'
;
  
;
Example 1 - example corresponding to the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~. Each reflection class is
                defined by the number m=sum|m~i~|, where the m~i~ are the
                integer coefficients that, in addition to h,k,l, index the
                corresponding diffraction vector in the basis defined for
                the reciprocal lattice.
;
 

 loop_
   _category_mandatory.name                                                   
  '_diffrn_reflns_class_code'

_publ_body_title
_category 'publ_body'
_definition 'Title of the associated section of text.'
_list  yes 
_list_reference '_publ_body_label'
_name '_publ_body_title'
_type  char 
_type_conditions  none 

_computing_data_reduction
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_data_reduction'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_reflns_shell_number_unique_gt
_category 'reflns_shell'
_definition
 
;
The total number of significantly intense reflections
               (see _reflns_threshold_expression) resulting from merging
               measured symmetry-equivalent reflections for this resolution
               shell.
;

_enumeration_range  0: 
_list  yes 
_name '_reflns_shell_number_unique_gt'
_related_function  alternate 
_related_item '_reflns_shell_number_unique_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_aniso_B_33
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_33'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_diffrn_orient_refln_angle_chi
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_chi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_diffrn_radiation_wavelength_[]
_category 'category_overview'
_category.id 'diffrn_radiation_wavelength'
_definition
 
;
Data items in the DIFFRN_RADIATION_WAVELENGTH category describe
               the wavelength of the radiation used in measuring diffraction
               intensities. Items may be looped to identify and assign weights
               to distinct wavelength components from a polychromatic beam.
;

_list  no 
_name '_diffrn_radiation_wavelength_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  '_diffrn_radiation_wavelength       1.5418' 
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_diffrn_radiation_wavelength_id'

_exptl_crystal_face_diffr_psi
_category 'exptl_crystal_face'
_definition
 
;
The goniometer angle settings in degrees when the perpendicular
               to the specified crystal face is aligned along a specified
               direction (e.g. the bisector of the incident and reflected beams
               in an optical goniometer).

;

_list  yes 
_list_reference '_exptl_crystal_face_index_'
_name '_exptl_crystal_face_diffr_psi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_atom_type_scat_Cromer_Mann_a4
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_a4'
_type  numb 
_type_conditions  none 

_atom_site_calc_attached_atom
_category 'atom_site'
_definition
 
;
The _atom_site_label of the atom site to which the 'geometry-
               calculated' atom site is attached.
;

_enumeration_default  . 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_calc_attached_atom'
_type  char 
_type_conditions  none 

_cell_measurement_temperature
_category  cell 
_definition
 
;
The temperature in kelvins at which the unit-cell parameters
               were measured (not the temperature of synthesis).
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_measurement_temperature'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_[]
_category 'category_overview'
_category.id 'diffrn_refln'
_definition
 
;
Data items in the DIFFRN_REFLN category record details about
               the intensities measured in the diffraction experiment.

               The DIFFRN_REFLN data items refer to individual intensity
               measurements, and must be included in looped lists.

               (The DIFFRN_REFLNS data items specify the parameters that apply
               to all intensity  measurements. The DIFFRN_REFLNS data items
               are not looped.)
;

_list  no 
_name '_diffrn_refln_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
        _diffrn_refln_index_h
        _diffrn_refln_index_k
        _diffrn_refln_index_l
        _diffrn_refln_angle_chi
        _diffrn_refln_scan_rate
        _diffrn_refln_counts_bg_1
        _diffrn_refln_counts_total
        _diffrn_refln_counts_bg_2
        _diffrn_refln_angle_theta
        _diffrn_refln_angle_phi
        _diffrn_refln_angle_omega
        _diffrn_refln_angle_kappa
        _diffrn_refln_scan_width
        _diffrn_refln_elapsed_time

 0  0 -16  0. 4.12  28 127  36  33.157  -75.846  16.404   50.170  1.516 19.43
 0  0 -15  0. 4.12  38 143  28  30.847  -75.846  14.094   50.170  1.516 19.82
 0  0 -14  0. 1.03 142 742 130  28.592  -75.846  11.839   50.170  1.516 21.32
 0  0 -13  0. 4.12  26 120  37  26.384  -75.846   9.631   50.170  1.450 21.68
 0  0 -12  0. 0.97 129 618 153  24.218  -75.846   7.464   50.170  1.450 23.20
 0  0 -11  0. 4.12  33 107  38  22.087  -75.846   5.334   50.170  1.384 23.55
 0  0 -10  0. 4.12  37 146  33  19.989  -75.846   3.235   50.170  1.384 23.90
 0  0  -9  0. 4.12  50 179  49  17.918  -75.846   1.164   50.170  1.384 24.25
    # - - - - data truncated for brevity - - - -
 3  4  -4  0. 1.03  69 459  73  30.726  -53.744  46.543  -47.552  1.516 2082.58
 3  4  -5  0. 1.03  91 465  75  31.407  -54.811  45.519  -42.705  1.516 2084.07
 3 14  -6  0. 1.03  84 560  79  32.228  -55.841  44.745  -38.092  1.516 2085.57
    # - - - - data truncated for brevity - - - -
;
  
;
Example 1 - extracted from the CAD-4 listing of Tl~2~Cd~2~(SO~4~)~3~ at
                85 K (unpublished).
;
 

 loop_
   _category_mandatory.name                                                   
  '_diffrn_refln_index_l'
  '_diffrn_refln_index_k'
  '_diffrn_refln_index_h'

_journal_issue
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_issue'
_type  char 
_type_conditions  none 

_atom_site_Cartn_x
_category 'atom_site'
_definition
 
;
The atom site coordinates in angstroms specified according to a
               set of orthogonal Cartesian axes related to the cell axes as
               specified by the _atom_sites_Cartn_transform_axes description.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_Cartn_x'
_related_function  alternate 
_related_item '_atom_site_fract_'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

_publ_manuscript_incl_extra_defn
_category 'publ_manuscript_incl'
_definition
 
;
Flags whether the corresponding data item marked for inclusion
               in a journal request list is a standard CIF definition or not.
;

_enumeration_default  yes 
_list  yes 
_list_reference '_publ_manuscript_incl_extra_item'
_name '_publ_manuscript_incl_extra_defn'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'not a standard CIF data name'
   n  'abbreviation for "no"'
   yes  'a standard CIF data name'
   y  'abbreviation for "yes"'

_atom_site_Cartn_z
_category 'atom_site'
_definition
 
;
The atom site coordinates in angstroms specified according to a
               set of orthogonal Cartesian axes related to the cell axes as
               specified by the _atom_sites_Cartn_transform_axes description.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_Cartn_z'
_related_function  alternate 
_related_item '_atom_site_fract_'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

_cell_reciprocal_angle_alpha
_category  cell 
_definition
 
;
The angles in degrees defining the reciprocal cell. These
               are related to those in the real cell by:

               cos(recip-alpha)
                   = [cos(beta)*cos(gamma) - cos(alpha)]/[sin(beta)*sin(gamma)]

               cos(recip-beta)
                   = [cos(gamma)*cos(alpha) - cos(beta)]/[sin(gamma)*sin(alpha)]

               cos(recip-gamma)
                   = [cos(alpha)*cos(beta) - cos(gamma)]/[sin(alpha)*sin(beta)]

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_reciprocal_angle_alpha'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_exptl_crystal_face_diffr_chi
_category 'exptl_crystal_face'
_definition
 
;
The goniometer angle settings in degrees when the perpendicular
               to the specified crystal face is aligned along a specified
               direction (e.g. the bisector of the incident and reflected beams
               in an optical goniometer).

;

_list  yes 
_list_reference '_exptl_crystal_face_index_'
_name '_exptl_crystal_face_diffr_chi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_reflns_shell_percent_possible_all
_category 'reflns_shell'
_definition
 
;
The percentage of geometrically possible reflections
               represented by all reflections measured for this
               resolution shell.
;

_enumeration_range  0.0:100.0 
_list  yes 
_name '_reflns_shell_percent_possible_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   100.0   100.0 
   100.0   0.0 
   0.0   0.0 

_atom_site_aniso_B_22
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_22'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_atom_site_aniso_B_23
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_23'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_reflns_class_description
_category 'reflns_class'
_definition 'Description of each reflection class.'
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_description'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'm=1 first order satellites'
  'H0L0 common projection reflections'

_diffrn_refln_attenuator_code
_category 'diffrn_refln'
_definition
 
;
The code identifying the attenuator setting for this reflection.
               This code must match one of the _diffrn_attenuator_code values.
;

_list  yes 
_list_link_parent '_diffrn_attenuator_code'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_attenuator_code'
_type  char 
_type_conditions  none 

_exptl_crystal_recrystallization_method
_category 'exptl_crystal'
_definition
 
;
Describes the method used to recrystallize the sample. 
               Sufficient details should be given for the procedure to be
               repeated.  The temperature or temperatures should be given as
               well as details of the solvent, flux or carrier gas with
               concentrations or pressures and ambient atmosphere.
;

_list  no 
_name '_exptl_crystal_recrystallization_method'
_type  char 
_type_conditions  none 

_exptl_crystal_size_rad
_category 'exptl_crystal'
_definition
 
;
The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere then the *_rad item is
               its radius. If the crystal is a cylinder then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_size_rad'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_intensity_net
_category 'diffrn_refln'
_definition
 
;
Net intensity calculated from the diffraction counts after
               the attenuator and standard scales have been applied.
;

_enumeration_range  0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_intensity_net'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_bond_distance
_category 'geom_bond'
_definition 'The intramolecular bond distance in angstroms.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_geom_bond_atom_site_label_'
_name '_geom_bond_distance'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_angle_site_symmetry_3
_category 'geom_angle'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_angle_atom_site_label_'
_name '_geom_angle_site_symmetry_3'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_refine_ls_class_d_res_low
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the lowest resolution in angstroms
               for the spacing in the reflections used in refinement. This is
               the highest d value in a reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_d_res_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_hbond_publ_flag
_category 'geom_hbond'
_definition
 
;
This code signals if the hydrogen bond information is referred
               to in a publication or should be placed in a table of
               significant hydrogen-bond geometry.
;

_enumeration_default  no 
_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_publ_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'do not include bond in special list'
   n  'abbreviation for "no"'
   yes  'do include bond in special list'
   y  'abbreviation for "yes"'

_atom_site_label_component_0
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_0'
_type  char 
_type_conditions  none 

_citation_book_publisher
_category  citation 
_definition
 
;
The name of the publisher of the citation; relevant
               for book chapters.
;

_example 'John Wiley'
_list  yes 
_list_reference '_citation_id'
_name '_citation_book_publisher'
_type  char 
_type_conditions  none 

_atom_site_label_component_2
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_2'
_type  char 
_type_conditions  none 

_diffrn_reflns_class_d_res_low
_category 'diffrn_reflns_class'
_definition
 
;
The lowest resolution in angstroms for the interplanar
               spacing in the reflections of each measured reflection class.
               This is the largest d value for this reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_d_res_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_Rmerge_I_gt
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(I) for significantly intense reflections
               (see _reflns_threshold_expression) in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_I_gt'
_related_function  alternate 
_related_item '_reflns_shell_Rmerge_I_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_label_component_5
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_5'
_type  char 
_type_conditions  none 

_atom_site_label_component_6
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_6'
_type  char 
_type_conditions  none 

_atom_site_aniso_U_33
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_33'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_citation_editor_name
_category 'citation_editor'
_definition
 
;
Name of an editor of the citation;  relevant for book chapters.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

_list  yes 
_list_mandatory  yes 
_name '_citation_editor_name'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Bleary, Percival R.'
  "O'Neil, F.K."
  'Van den Bossche, G.'
  'Yang, D.-L.'
  'Simonov, Yu.A'
  'M\"uller, H.A.'
  'Ross II, C.R.'

_diffrn_source_power
_category 'diffrn_source'
_definition
 
;
The power in kilowatts at which the radiation source was
               operated.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_source_power'
_type  numb 
_type_conditions  none 
_units  kW 
_units_detail  kilowatts 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_transf_matrix_13
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_13'
_type  numb 
_type_conditions  none 

_diffrn_refln_wavelength_id
_category 'diffrn_refln'
_definition 'Code identifying the wavelength in the _diffrn_radiation_ list.'
_list  yes 
_list_link_parent '_diffrn_radiation_wavelength_id'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_wavelength_id'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   x1 
   x2 
   neut 

_diffrn_reflns_transf_matrix_11
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_11'
_type  numb 
_type_conditions  none 

_exptl_crystal_pressure_history
_category 'exptl_crystal'
_definition
 
;
Relevant details concerning the pressure history of the
               sample.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_pressure_history'
_type  char 
_type_conditions  none 

_citation_title
_category  citation 
_definition
 
;
The title of the citation;  relevant for both journal articles
               and book chapters.
;

_example
 
;
Structure of Diferric Duck Ovotransferrin at 2.35 \%A
                        Resolution.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_title'
_type  char 
_type_conditions  none 

_refine_ls_d_res_high
_category  refine 
_definition
 
;
The highest resolution in angstroms for the interplanar spacing
               in the reflections used in refinement. This is the smallest
               d value.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_d_res_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_measured_fraction_theta_full
_category  diffrn 
_definition
 
;
Fraction of unique (symmetry-independent) reflections measured
          out to _diffrn_reflns_theta_full.
;

_enumeration_range  0:1.0 
_list  yes 
_name '_diffrn_measured_fraction_theta_full'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_cell_measurement_pressure
_category  cell 
_definition
 
;
The pressure in kilopascals at which the unit-cell parameters
               were measured (not the pressure used to synthesize the sample).
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_measurement_pressure'
_type  numb 
_type_conditions  esd 
_units  kPa 
_units_detail  kilopascals 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_detector_type
_category 'diffrn_detector'
_definition 'The make, model or name of the detector device used.'
_list  no 
_name '_diffrn_detector_type'
_type  char 
_type_conditions  none 

_diffrn_source_[]
_category 'category_overview'
_category.id 'diffrn_source'
_definition
 
;
Data items in the DIFFRN_SOURCE category record details of
               the source of radiation used in the diffraction experiment.
;

_list  no 
_name '_diffrn_source_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_source               'rotating anode X-ray tube'
    _diffrn_source_type          'Rigaku RU-200'
    _diffrn_source_power         50
    _diffrn_source_current       180
    _diffrn_source_size          '8 mm x 0.4 mm broad focus'
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

_atom_site_B_iso_or_equiv
_category 'atom_site'
_definition
 
;
Isotropic atomic displacement parameter, or equivalent isotropic
               atomic displacement parameter, B(equiv), in angstroms squared,
               calculated from anisotropic temperature factor parameters.

               B(equiv) = (1/3) sum~i~[sum~j~(B^ij^ a*~i~ a*~j~ a~i~ a~j~)]

               a     = the real-space cell lengths
               a*    = the reciprocal-space cell lengths
               B^ij^ = 8 pi^2^ U^ij^

               Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44,
                    775-776.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_B_iso_or_equiv'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_atom_site_B_equiv_geom_mean'
   conversion  '_atom_site_U_iso_or_equiv'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_author_[]
_category 'category_overview'
_category.id 'citation_author'
_definition
 
;
Data items in the CITATION_AUTHOR category record details
               about the authors associated with the citations in the
               _citation_ list.
;

_list  no 
_name '_citation_author_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _citation_author_citation_id
    _citation_author_name
      primary  'Fitzgerald, P.M.D.'
      primary  'McKeever, B.M.'
      primary  'Van Middlesworth, J.F.'
      primary  'Springer, J.P.'
      primary  'Heimbach, J.C.'
      primary  'Leu, C.-T.'
      primary  'Herber, W.K.'
      primary  'Dixon, R.A.F.'
      primary  'Darke, P.L.'
      2        'Navia, M.A.'
      2        'Fitzgerald, P.M.D.'
      2        'McKeever, B.M.'
      2        'Leu, C.-T.'
      2        'Heimbach, J.C.'
      2        'Herber, W.K.'
      2        'Sigal, I.S.'
      2        'Darke, P.L.'
      2        'Springer, J.P.'
      3        'McKeever, B.M.'
      3        'Navia, M.A.'
      3        'Fitzgerald, P.M.D.'
      3        'Springer, J.P.'
      3        'Leu, C.-T.'
      3        'Heimbach, J.C.'
      3        'Herber, W.K.'
      3        'Sigal, I.S.'
      3        'Darke, P.L.'
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

 loop_
   _category_mandatory.name                                                   
  '_citation_author_citation_id'
  '_citation_author_name'

_publ_contact_author_name
_category  publ 
_definition
 
;
The name of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff.
;

_example 'Professor George Ferguson'
_list  no 
_name '_publ_contact_author_name'
_type  char 
_type_conditions  none 

_publ_author_id_iucr
_category 'publ_author'
_definition
 
;
Identifier in the IUCr contact database of a publication
               author.  This identifier may be available from the World
               Directory of Crystallographers (http://wdc.iucr.org).
;

_example  2985 
_list  yes 
_name '_publ_author_id_iucr'
_type  char 
_type_conditions  none 

_reflns_class_number_gt
_category 'reflns_class'
_definition
 
;
For each reflection class, the number of significantly intense
               reflections (see _reflns_threshold_expression) in the _refln_
               list (not the _diffrn_refln_ list). It may include Friedel
               equivalent reflections (i.e. those which are symmetry equivalent
               under the Laue symmetry but inequivalent under the crystal
               class)  according to the nature of the structure and the
               procedures used. The special characteristics of the reflections
               included in the _refln_ list should be given in the item
               _reflns_special_details.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_number_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_contact_site_symmetry_1
_category 'geom_contact'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the contact. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_contact_atom_site_label_'
_name '_geom_contact_site_symmetry_1'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_geom_contact_site_symmetry_2
_category 'geom_contact'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the contact. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_contact_atom_site_label_'
_name '_geom_contact_site_symmetry_2'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_valence_param_atom_2
_category 'valence_param'
_definition
 
;
The element symbol of the second atom forming the bond whose
               bond valence parameters are given in this category.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_atom_2'
_type  char 
_type_conditions  none 

_journal_coeditor_notes
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_notes'
_type  char 
_type_conditions  none 

_diffrn_reflns_class_av_R_eq
_category 'diffrn_reflns_class'
_definition
 
;
For each reflection class, the residual
               [sum av|del(I)|/sum|av(I)|] for symmetry-equivalent reflections
               used to calculate the average intensity av(I). The av|del(I)|
               term is the average absolute difference between av(I) and the
               individual intensities.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_av_R_eq'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_phase_calc
_category  refln 
_definition 'The calculated structure-factor phase in degrees.'
_list  yes 
_list_reference '_refln_index_'
_name '_refln_phase_calc'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_journal_[]
_category 'category_overview'
_category.id  journal 
_definition
 
;
Data items in the JOURNAL category record details about the
               book keeping entries used by the journal staff when processing
               a CIF submitted for publication.

               Normally the creator of a CIF will not specify these data items.
               The data names are not defined in the Dictionary because they are
               for journal use only.
;

_list  no 
_name '_journal_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_journal_date_recd_electronic     91-04-15
    _journal_date_from_coeditor       91-04-18
    _journal_date_accepted            91-04-18
    _journal_date_printers_first      91-08-07
    _journal_date_proofs_out          91-08-07
    _journal_coeditor_code            HL0007
    _journal_techeditor_code          C910963
    _journal_coden_ASTM               ACSCEE
    _journal_name_full
                                      'Acta Crystallographica Section C'
    _journal_year                     1991
    _journal_volume                   47
    _journal_issue                    NOV91
    _journal_page_first               2276
    _journal_page_last                2277
;
  
;
Example 1 - based on Acta Cryst. file for entry HL0007 [Willis, Beckwith
                & Tozer (1991). Acta Cryst. C47, 2276-2277].
;
 

_journal_index_[]
_category 'category_overview'
_category.id 'journal_index'
_definition
 
;
Data items in the JOURNAL_INDEX category are used to list
               terms employed in generating the journal indexes.

               Normally the creator of a CIF will not specify these data items.
;

_list  no 
_name '_journal_index_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _journal_index_type
    _journal_index_term
    _journal_index_subterm
      O   C16H19NO4            .
      S   alkaloids           (-)-norcocaine
      S   (-)-norcocaine       .
      S
    ;  [2R,3S-(2\b,3\b)]-methyl
       3-(benzoyloxy)-8-azabicyclo[3.2.1]octane-2-carboxylate
    ;                          .
;
  
;
Example 1 - based on a paper by Zhu, Reynolds, Klein & Trudell [(1994).
                Acta Cryst. C50, 2067-2069].
;
 

_exptl_crystal_density_meas_temp
_category 'exptl_crystal'
_definition
 
;
Temperature in kelvins at which _exptl_crystal_density_meas
               was determined.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas_temp'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_goodness_of_fit_obs
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S for observed
               reflections (see _reflns_observed_criterion), after the final
               cycle of refinement. Ideally, account should be taken of
               parameters restrained in the least squares. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty (e.s.d.)

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_goodness_of_fit_obs'
_related_function  replace 
_related_item '_refine_ls_goodness_of_fit_gt'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_special_details
_category  exptl 
_definition
 
;
Any special information about the experimental work prior to the
               intensity measurement. See also _exptl_crystal_preparation.
;

_list  no 
_name '_exptl_special_details'
_type  char 
_type_conditions  none 

_reflns_[]
_category 'category_overview'
_category.id  reflns 
_definition
 
;
Data items in the REFLNS category record details about the
               reflections used to determine the ATOM_SITE data items.

               The REFLN data items refer to individual reflections and must
               be included in looped lists.

               The REFLNS data items specify the parameters that apply to all
               reflections. The REFLNS data items are not looped.
;

_list  no 
_name '_reflns_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_reflns_limit_h_min                0
    _reflns_limit_h_max                6
    _reflns_limit_k_min                0
    _reflns_limit_k_max                17
    _reflns_limit_l_min                0
    _reflns_limit_l_max                22
    _reflns_number_total               1592
    _reflns_number_gt                  1408
    _reflns_threshold_expression       'F > 6.0u(F)'
    _reflns_d_resolution_high          0.8733
    _reflns_d_resolution_low           11.9202
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_diffrn_reflns_reduction_process
_category 'diffrn_reflns'
_definition
 
;
A description of the process used to reduce the intensities
               into structure-factor magnitudes.
;

_example 'data averaged using Fisher test'
_list  no 
_name '_diffrn_reflns_reduction_process'
_type  char 
_type_conditions  none 

_atom_site_aniso_B_12
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_12'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_space_group_crystal_system
_category 'space_group'
_definition
 
;
The name of the system of geometric crystal classes of space
               groups (crystal system) to which the space group belongs.
               Note that rhombohedral space groups belong to the
               trigonal system.
;

_list  both 
_list_reference '_space_group_id'
_name '_space_group_crystal_system'
_related_function  alternate 
_related_item '_symmetry_cell_setting'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   triclinic 
   monoclinic 
   orthorhombic 
   tetragonal 
   trigonal 
   hexagonal 
   cubic 

_computing_data_collection
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_data_collection'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_cell_reciprocal_length_b
_category  cell 
_definition
 
;
The reciprocal cell lengths in inverse Angstroms.  These are 
               related to the real cell by the following equation:

               recip-a = b*c*sin(alpha)/V

               recip-b = c*a*sin(beta)/V

               recip-c = a*b*sin(gamma)/V

               where V is the cell volume.

               Ref: Buerger, M.J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_reciprocal_length_b'
_type  numb 
_type_conditions  esd 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_F_calc
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the structure factors (in electrons for
               X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_calc'
_type  numb 
_type_conditions  none 

_reflns_limit_l_max
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_l_max'
_type  numb 
_type_conditions  none 

_exptl_crystal_[]
_category 'category_overview'
_category.id 'exptl_crystal'
_definition
 
;
Data items in the EXPTL_CRYSTAL category record details about
               experimental measurements on the crystal or crystals used,
               such as shape, size, density, and so on.
;

_list  no 
_name '_exptl_crystal_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_exptl_crystal_description          prism
    _exptl_crystal_colour               colourless
    _exptl_crystal_size_max             0.32
    _exptl_crystal_size_mid             0.27
    _exptl_crystal_size_min             0.10
    _exptl_crystal_density_diffrn       1.146
    _exptl_crystal_density_meas         ?
    _exptl_crystal_density_method       'not measured'
    _exptl_crystal_F_000                656
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_exptl_crystal_id'

_exptl_crystal_density_diffrn
_category 'exptl_crystal'
_definition
 
;
Density values calculated from crystal cell and contents. The
               units are megagrams per cubic metre (grams per cubic centimetre).
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_diffrn'
_type  numb 
_type_conditions  none 
_units  Mgm^-3^ 
_units_detail 'megagrams per cubic metre'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_coeditor_fax
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_coeditor_fax'
_type  char 
_type_conditions  none 

_exptl_crystal_size_mid
_category 'exptl_crystal'
_definition
 
;
The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere then the *_rad item is
               its radius. If the crystal is a cylinder then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_size_mid'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_meanI_over_sigI_all
_category 'reflns_shell'
_definition
 
;
The ratio of the mean of the intensities of all reflections
               in this shell to the mean of the standard uncertainties of the
               intensities of all reflections in the resolution shell.
;

_list  yes 
_name '_reflns_shell_meanI_over_sigI_all'
_related_function  replace 
_related_item '_reflns_shell_meanI_over_uI_all'
_type  numb 
_type_conditions  none 

_exptl_crystal_size_min
_category 'exptl_crystal'
_definition
 
;
The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere then the *_rad item is
               its radius. If the crystal is a cylinder then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_size_min'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_intensity_calc
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the intensity, in the measured units.
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_intensity_calc'
_type  numb 
_type_conditions  none 

_refine_ls_shift/su_max_lt
_category  refine 
_definition
 
;
An upper limit for the largest (ratio of the final
               least-squares parameter shift divided by the final 
               standard uncertainty).  This item is used when the largest
               value of the shift divided by the final standard uncertainty
               is too small to measure.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/su_max_lt'
_related_function  alternate 
_related_item '_refine_ls_shift/su_max'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_date_printers_final
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_printers_final'
_type  char 
_type_conditions  none 

_diffrn_standard_refln_code
_category 'diffrn_standard_refln'
_definition
 
;
The code identifying a reflection measured as a standard
               reflection with the indices _diffrn_standard_refln_index_.
               This is the same code as the  _diffrn_refln_standard_code in
               the _diffrn_refln_ list.
;

_list  yes 
_list_link_child '_diffrn_refln_standard_code'
_list_reference '_diffrn_standard_refln_index_'
_name '_diffrn_standard_refln_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   2 
   3 
   s1 
   A 
   B 

_publ_section_exptl_solution
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_exptl_solution'
_type  char 
_type_conditions  none 

_diffrn_refln_elapsed_time
_category 'diffrn_refln'
_definition
 
;
Elapsed time in minutes from the start of diffraction
               measurement to the measurement of this intensity.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_elapsed_time'
_type  numb 
_type_conditions  none 
_units  min 
_units_detail  minutes 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_shell_number_measured_obs
_category 'reflns_shell'
_definition
 
;
The number of reflections classified as 'observed'
               (see _reflns_observed_criterion) measured for this
               resolution shell.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_number_measured_obs'
_related_function  replace 
_related_item '_reflns_shell_number_measured_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_crystal_face_[]
_category 'category_overview'
_category.id 'exptl_crystal_face'
_definition
 
;
Data items in the EXPTL_CRYSTAL_FACE category record details
               of the crystal faces.
;

_list  no 
_name '_exptl_crystal_face_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _exptl_crystal_face_index_h
    _exptl_crystal_face_index_k
    _exptl_crystal_face_index_l
    _exptl_crystal_face_perp_dist
         0   -1   -2    .18274
         1    0   -2    .17571
        -1    1   -2    .17845
        -2    1    0    .21010
        -1    0    2    .18849
         1   -1    2    .20605
         2   -1    0    .24680
        -1    2    0    .19688
         0    1    2    .15206
;
  
;
Example 1 - based on structure PAWD2 of Vittal & Dean [(1996). Acta
                Cryst. C52, 1180-1182].
;
 

 loop_
   _category_mandatory.name                                                   
  '_exptl_crystal_face_index_l'
  '_exptl_crystal_face_index_k'
  '_exptl_crystal_face_index_h'

_atom_site_attached_hydrogens
_category 'atom_site'
_definition
 
;
The number of hydrogen atoms attached to the atom at this site
               excluding any H atoms for which coordinates (measured or
               calculated) are given.
;

_enumeration_default  0 
_enumeration_range  0:8 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_attached_hydrogens'
_type  numb 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   2  'water oxygen'
   1  'hydroxyl oxygen'
   4  'ammonium nitrogen'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   8.0   8.0 
   8.0   0.0 
   0.0   0.0 

_citation_journal_volume
_category  citation 
_definition
 
;
Volume number of the journal cited;  relevant for journal
               articles.
;

_example  174 
_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_volume'
_type  char 
_type_conditions  none 

_diffrn_reflns_theta_full
_category 'diffrn_reflns'
_definition
 
;
The theta angle (in degrees) at which the measured reflection
               count is close to complete. The fraction of unique reflections
               measured out to this angle is given by
               _diffrn_measured_fraction_theta_full.
;

_enumeration_range  0.0:90.0 
_list  no 
_name '_diffrn_reflns_theta_full'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_atom_sites_fract_tran_matrix_22
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_22'
_type  numb 
_type_conditions  none 

_geom_torsion_site_symmetry_4
_category 'geom_torsion'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion_site_symmetry_4'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_publ_requested_category
_category  publ 
_definition
 
;
The category of paper submitted. For submission to Acta
               Crystallographica Section C or Acta Crystallographica
               Section E, ONLY those codes indicated for use with those
               journals should be used.
;

_enumeration_default  FA 
_list  no 
_name '_publ_requested_category'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   FA  'Full article'
   FI  'Full submission - inorganic (Acta C)'
   FO  'Full submission - organic (Acta C)'
   FM  'Full submission - metal-organic (Acta C)'
   CI  'CIF-access paper - inorganic (Acta C)'
   CO  'CIF-access paper - organic (Acta C)'
   CM  'CIF-access paper - metal-organic (Acta C)'
   EI  'Electronic submission - inorganic (Acta E)'
   EO  'Electronic submission - organic (Acta E)'
   EM  'Electronic submission - metal-organic (Acta E)'
   AD  'Addenda & Errata (Acta C, Acta E)'
   SC  'Short Communication'

_chemical_conn_bond_type
_category 'chemical_conn_bond'
_definition
 
;
The chemical bond type associated with the connection between
               the two sites _chemical_conn_bond_atom_1 and *_2.
;

_enumeration_default  sing 
_list  yes 
_list_reference '_chemical_conn_bond_atom_'
_name '_chemical_conn_bond_type'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   sing  'single bond'
   doub  'double bond'
   trip  'triple bond'
   quad  'quadruple bond'
   arom  'aromatic bond'
   poly  'polymeric bond'
   delo  'delocalized double bond'
   pi  'pi bond'

_chemical_name_common
_category  chemical 
_definition 'Trivial name by which the compound is commonly known.'
_example  1-bromoestradiol 
_list  no 
_name '_chemical_name_common'
_type  char 
_type_conditions  none 

_diffrn_orient_matrix_UB_33
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_33'
_type  numb 
_type_conditions  none 

_reflns_class_d_res_high
_category 'reflns_class'
_definition
 
;
For each reflection class the highest resolution in angstroms
               for the interplanar spacing in the reflections used in
               refinement. This is the smallest d value.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_d_res_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_section_introduction
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_introduction'
_type  char 
_type_conditions  none 

_symmetry_equiv_pos_as_xyz
_category 'symmetry_equiv'
_definition
 
;
Symmetry equivalent position in the 'xyz' representation. Except
               for the space group P1, this data will be repeated in a loop.
               The format of the data item is as per International Tables for
               Crystallography, Vol. A. (1987). All equivalent positions should
               be entered, including those for lattice centring and a centre of
               symmetry, if present.
;

_example  -y+x,-y,1/3+z 
_list  both 
_name '_symmetry_equiv_pos_as_xyz'
_related_function  replace 
_related_item '_space_group_symop_operation_xyz'
_type  char 
_type_conditions  none 

_atom_type_scat_dispersion_imag
_category 'atom_type'
_definition
 
;
The imaginary and real components of the anomalous dispersion
               scattering factors, f'' and f', in electrons, for this atom type
               and the radiation given in _diffrn_radiation_wavelength.
;

_enumeration_default  0.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_dispersion_imag'
_type  numb 
_type_conditions  none 

_exptl_crystal_colour_modifier
_category 'exptl_crystal'
_definition
 
;
The enumeration list of standardized names developed for the
              International Center for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green', 
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_colour_modifier'
_related_function  alternate 
_related_item '_exptl_crystal_colour'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   light 
   dark 
   whitish 
   blackish 
   grayish 
   brownish 
   reddish 
   pinkish 
   orangish 
   yellowish 
   greenish 
   bluish 

_geom_angle_[]
_category 'category_overview'
_category.id 'geom_angle'
_definition
 
;
Data items in the GEOM_ANGLE category record details about the
               bond angles, as calculated from the contents of the ATOM,
               CELL, and SYMMETRY data.
;

_list  no 
_name '_geom_angle_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _geom_angle_atom_site_label_1
    _geom_angle_atom_site_label_2
    _geom_angle_atom_site_label_3
    _geom_angle
    _geom_angle_site_symmetry_1
    _geom_angle_site_symmetry_2
    _geom_angle_site_symmetry_3
    _geom_angle_publ_flag
     C2  O1  C5   111.6(2)  1_555  1_555  1_555  yes
     O1  C2  C3   110.9(2)  1_555  1_555  1_555  yes
     O1  C2  O21  122.2(3)  1_555  1_555  1_555  yes
     C3  C2  O21  127.0(3)  1_555  1_555  1_555  yes
     C2  C3  N4   101.3(2)  1_555  1_555  1_555  yes
     C2  C3  C31  111.3(2)  1_555  1_555  1_555  yes
     C2  C3  H3   107(1)    1_555  1_555  1_555  no
     N4  C3  C31  116.7(2)  1_555  1_555  1_555  yes
    # - - - - data truncated for brevity - - - -
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_geom_angle_atom_site_label_2'
  '_geom_angle_atom_site_label_3'
  '_geom_angle_atom_site_label_1'

_atom_type_symbol
_category 'atom_type'
_definition
 
;
The code used to identify the atom specie(s) representing this
               atom type. Normally this code is the element symbol. The code
               may be composed of any character except an underline with the
               additional proviso that digits designate an oxidation state and
               must be followed by a + or - character.
;

_list  yes 
_list_link_child '_atom_site_type_symbol'
_list_mandatory  yes 
_name '_atom_type_symbol'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   C 
   Cu2+ 
   H(SDS) 
   dummy 
   FeNi 

_diffrn_reflns_class_av_uI/I
_category 'diffrn_reflns_class'
_definition
 
;
Measure [sum|u(net I)|/sum|net I|] for all measured intensities
               in a reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_av_uI/I'
_related_function  alternate 
_related_item '_diffrn_reflns_class_av_sgI/I'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_radiation_detector
_category 'diffrn_detector'
_definition 'The detector used to measure the diffraction intensities.'
_list  no 
_name '_diffrn_radiation_detector'
_related_function  replace 
_related_item '_diffrn_detector'
_type  char 
_type_conditions  none 

_valence_param_atom_1_valence
_category 'valence_param'
_definition
 
;
The valence (formal charge) of the first atom whose bond
               valence parameters are given in this category.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_atom_1_valence'
_type  numb 
_type_conditions  none 

_atom_type_scat_dispersion_source
_category 'atom_type'
_definition
 
;
Reference to source of real and imaginary dispersion
               corrections for scattering factors used for this atom type.
;

_example 'International Tables Vol. IV Table 2.3.1'
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_dispersion_source'
_type  char 
_type_conditions  none 

_atom_site_[]
_category 'category_overview'
_category.id 'atom_site'
_definition
 
;
Data items in the ATOM_SITE category record details about
               the atom sites in a crystal structure, such as the positional
               coordinates, atomic displacement parameters, magnetic moments
               and directions, and so on.
;

_list  no 
_name '_atom_site_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _atom_site_label
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
    _atom_site_adp_type
    _atom_site_calc_flag
    _atom_site_calc_attached_atom
      O1   .4154(4)  .5699(1)  .3026(0)  .060(1)  Uani  ?    ?
      C2   .5630(5)  .5087(2)  .3246(1)  .060(2)  Uani  ?    ?
      C3   .5350(5)  .4920(2)  .3997(1)  .048(1)  Uani  ?    ?
      N4   .3570(3)  .5558(1)  .4167(0)  .039(1)  Uani  ?    ?
      C5   .3000(5)  .6122(2)  .3581(1)  .045(1)  Uani  ?    ?
      O21  .6958(5)  .4738(2)  .2874(1)  .090(2)  Uani  ?    ?
      C31  .4869(6)  .3929(2)  .4143(2)  .059(2)  Uani  ?    ?
     # - - - - data truncated for brevity - - - -
      H321C  .04(1)  .318(3)   .320(2)   .14000   Uiso  ?    ?
      H322A  .25(1)  .272(4)   .475(3)   .19000   Uiso  ?    ?
      H322B  .34976  .22118    .40954    .19000   Uiso  calc C322
      H322C  .08(1)  .234(4)   .397(3)   .19000   Uiso  ?    ?
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 
  
;
loop_
    _atom_site_aniso_label
    _atom_site_aniso_B_11
    _atom_site_aniso_B_22
    _atom_site_aniso_B_33
    _atom_site_aniso_B_12
    _atom_site_aniso_B_13
    _atom_site_aniso_B_23
    _atom_site_aniso_type_symbol
     O1   .071(1) .076(1) .0342(9) .008(1)   .0051(9) -.0030(9) O
     C2   .060(2) .072(2) .047(1)  .002(2)   .013(1)  -.009(1)  C
     C3   .038(1) .060(2) .044(1)  .007(1)   .001(1)  -.005(1)  C
     N4   .037(1) .048(1) .0325(9) .0025(9)  .0011(9) -.0011(9) N
     C5   .043(1) .060(1) .032(1)  .001(1)  -.001(1)   .001(1)  C
     # - - - - data truncated for brevity - - - -
     O21  .094(2) .109(2) .068(1)  .023(2)   .038(1)  -.010(1)  O
     C51  .048(2) .059(2) .049(1)  .002(1)  -.000(1)   .007(1)  C
     C511 .048(2) .071(2) .097(3) -.008(2)  -.003(2)   .010(2)  C
     C512 .078(2) .083(2) .075(2)  .009(2)  -.005(2)   .033(2)  C
     C513 .074(2) .055(2) .075(2)  .004(2)   .001(2)  -.010(2)  C
     # - - - - data truncated for brevity - - - -
;
  
;
Example 2 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 
  
;
loop_
    _atom_site_label
    _atom_site_chemical_conn_number
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
     S1  1  0.74799(9)  -0.12482(11)  0.27574(9)  0.0742(3)
     S2  2  1.08535(10)  0.16131(9)   0.34061(9)  0.0741(3)
     N1  3  1.0650(2)   -0.1390(2)    0.2918(2)   0.0500(5)
     C1  4  0.9619(3)   -0.0522(3)    0.3009(2)   0.0509(6)
     # - - - - data truncated for brevity - - - -
;
  
;
Example 3 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [(1996). Acta Cryst. C52, 951-953].
;
 
  
;
loop_
      _atom_site_label                  # *_assembly 'M' is a disordered methyl
      _atom_site_occupancy              # with configurations 'A' and 'B':
      _atom_site_disorder_assembly      #
      _atom_site_disorder_group         #    H11B    H11A      H13B
                                        #      .      |      .
   C1     1      .       .              #        .    |    .
   H11A   .5     M       A              #          .  |  .
   H12A   .5     M       A              #             C1 --------C2---
   H13A   .5     M       A              #           / .  \
   H11B   .5     M       B              #         /   .    \
   H12B   .5     M       B              #       /     .      \
   H13B   .5     M       B              #    H12A    H12B    H13A

;
  
;
Example 4 - Hypothetical example to illustrate the description of a
                disordered methyl group.
;
 

 loop_
   _category_mandatory.name                                                   
  '_atom_site_label'
  '_atom_site_aniso_label'

_cell_volume
_category  cell 
_definition
 
;
Cell volume V in angstroms cubed.

               V = a b c [1 - cos^2^(alpha) - cos^2^(beta) - cos^2^(gamma)
                           + 2 cos(alpha) cos(beta) cos(gamma) ] ^1/2^

               a     = _cell_length_a
               b     = _cell_length_b
               c     = _cell_length_c
               alpha = _cell_angle_alpha
               beta  = _cell_angle_beta
               gamma = _cell_angle_gamma
;

_enumeration_range  0.0: 
_list  no 
_name '_cell_volume'
_type  numb 
_type_conditions  esd 
_units  A^3^ 
_units_detail 'cubic angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_Cartn_y
_category 'atom_site'
_definition
 
;
The atom site coordinates in angstroms specified according to a
               set of orthogonal Cartesian axes related to the cell axes as
               specified by the _atom_sites_Cartn_transform_axes description.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_Cartn_y'
_related_function  alternate 
_related_item '_atom_site_fract_'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

_reflns_class_R_factor_all
_category 'reflns_class'
_definition
 
;
For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _reflns_class_d_res_high and _reflns_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _reflns_class_wR_factor_all definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_R_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_crystal_id
_category 'diffrn_refln'
_definition
 
;
Code identifying each crystal if multiple crystals are used. Is
               used to link with _exptl_crystal_id in the _exptl_crystal_ list.
;

_list  yes 
_list_link_parent '_exptl_crystal_id'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_crystal_id'
_type  char 
_type_conditions  none 

_refine_ls_abs_structure_details
_category  refine 
_definition 'The nature of the absolute structure and how it was determined.'
_list  no 
_name '_refine_ls_abs_structure_details'
_type  char 
_type_conditions  none 

_atom_site_chemical_conn_number
_category 'atom_site'
_definition
 
;
This number links an atom site to the chemical connectivity list.
               It must match a number specified by _chemical_conn_atom_number.
;

_enumeration_range  1: 
_list  yes 
_list_link_parent '_chemical_conn_atom_number'
_list_reference '_atom_site_label'
_name '_atom_site_chemical_conn_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_database_code_depnum_ccdc_journal
_category  database 
_definition
 
;
Deposition numbers assigned by various journals to files
               containing structural information archived by the Cambridge
               Crystallographic Data Centre (CCDC).
;

_list  no 
_name '_database_code_depnum_ccdc_journal'
_type  char 
_type_conditions  none 

_publ_contact_author_address
_category  publ 
_definition
 
;
The address of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff.
;

_example
 
;
Department of Chemistry and Biochemistry
                        University of Guelph
                        Ontario
                        Canada
                        N1G 2W1
;

_list  no 
_name '_publ_contact_author_address'
_type  char 
_type_conditions  none 

_refln_F_sigma
_category  refln 
_definition
 
;
The calculated, measured and standard uncertainty (derived from
               measurement) of the structure factors (in electrons for
               X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_sigma'
_type  numb 
_type_conditions  none 

_refln_A_calc
_category  refln 
_definition
 
;
The calculated and measured structure-factor component A
               (in electrons for X-ray diffraction).

               A =|F|cos(phase)
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_A_calc'
_type  numb 
_type_conditions  none 

_geom_angle_site_symmetry_2
_category 'geom_angle'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_angle_atom_site_label_'
_name '_geom_angle_site_symmetry_2'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_reflns_shell_meanI_over_sigI_gt
_category 'reflns_shell'
_definition
 
;
The ratio of the mean of the intensities of the significantly
               intense reflections (see _reflns_threshold_expression) in
               this shell to the mean of the standard uncertainties of the
               intensities of the significantly intense reflections in the
               resolution shell.
;

_list  yes 
_name '_reflns_shell_meanI_over_sigI_gt'
_related_function  replace 
_related_item '_reflns_shell_meanI_over_uI_gt'
_type  numb 
_type_conditions  none 

_geom_angle_site_symmetry_1
_category 'geom_angle'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_angle_atom_site_label_'
_name '_geom_angle_site_symmetry_1'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_atom_sites_fract_tran_matrix_13
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_13'
_type  numb 
_type_conditions  none 

_refine_[]
_category 'category_overview'
_category.id  refine 
_definition
 
;
Data items in the REFINE category record details about the
               structure refinement parameters.
;

_list  no 
_name '_refine_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_refine_special_details            sfls:_F_calc_weight_full_matrix

    _refine_ls_structure_factor_coef   F
    _refine_ls_matrix_type             full
    _refine_ls_weighting_scheme        calc
    _refine_ls_weighting_details      'w=1/(u^2^(F)+0.0004F^2^)'
    _refine_ls_hydrogen_treatment      refxyz
    _refine_ls_extinction_method       Zachariasen
    _refine_ls_extinction_coef         3514(42)
    _refine_ls_extinction_expression
    ;  Larson, A. C. (1970). "Crystallographic Computing",
       edited by F. R. Ahmed. Eq. (22) p. 292. Copenhagen: Munksgaard.
    ;
    _refine_ls_abs_structure_details
    ;      The absolute configuration was assigned to agree with that of
           its precursor l-leucine at the chiral centre C3.
    ;
    _refine_ls_number_reflns           1408
    _refine_ls_number_parameters       272
    _refine_ls_number_restraints       0
    _refine_ls_number_constraints      0
    _refine_ls_R_factor_all            .038
    _refine_ls_R_factor_gt             .034
    _refine_ls_wR_factor_all           .044
    _refine_ls_wR_factor_gt            .042
    _refine_ls_goodness_of_fit_all    1.462
    _refine_ls_goodness_of_fit_gt     1.515
    _refine_ls_shift/su_max            .535
    _refine_ls_shift/su_mean           .044
    _refine_diff_density_min          -.108
    _refine_diff_density_max           .131
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_atom_site_aniso_B_11
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_11'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_publ_manuscript_incl_extra_item
_category 'publ_manuscript_incl'
_definition
 
;
Specifies the inclusion of specific data into a manuscript
               which is not normally requested by the journal. The values
               of this item are the extra data names (which MUST be enclosed
               in single quotes) that will be added to the journal request list.
;

_list  yes 
_list_mandatory  yes 
_name '_publ_manuscript_incl_extra_item'
_type  char 
_type_conditions  none 

_atom_site_aniso_B_13
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the structure
               factor term:

               T = exp{-1/4 sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_B_13'
_related_function  conversion 
_related_item '_atom_site_aniso_U_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_citation_language
_category  citation 
_definition 'Language in which the citation appears.'
_example  german 
_list  yes 
_list_reference '_citation_id'
_name '_citation_language'
_type  char 
_type_conditions  none 

_refln_[]
_category 'category_overview'
_category.id  refln 
_definition
 
;
Data items in the REFLN category record details about the
               reflections used to determine the ATOM_SITE data items.

               The REFLN data items refer to individual reflections and must
               be included in looped lists.

               The REFLNS data items specify the parameters that apply to all
               reflections. The REFLNS data items are not looped.
;

_list  no 
_name '_refln_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
     _refln_index_h
     _refln_index_k
     _refln_index_l
     _refln_F_squared_calc
     _refln_F_squared_meas
     _refln_F_squared_sigma
     _refln_include_status
       2   0   0       85.57       58.90      1.45 o
       3   0   0    15718.18    15631.06     30.40 o
       4   0   0    55613.11    49840.09     61.86 o
       5   0   0      246.85      241.86     10.02 o
       6   0   0       82.16       69.97      1.93 o
       7   0   0     1133.62      947.79     11.78 o
       8   0   0     2558.04     2453.33     20.44 o
       9   0   0      283.88      393.66      7.79 o
       10  0   0      283.70      171.98      4.26 o
;
  
;
Example 1 - based on data set fetod of Todres, Yanovsky, Ermekov & Struchkov
                [(1993). Acta Cryst. C49, 1352-1354].
;
 
  
;
loop_
    _refln_index_h
    _refln_index_k
    _refln_index_l
    _refln_F_meas
    _refln_F_calc
    _refln_F_sigma
    _refln_include_status
    _refln_scale_group_code
        0   0   6  34.935  36.034   3.143  o  1
        0   0  12  42.599  40.855   2.131  o  1
        0   1   0  42.500  42.507   4.719  o  1
        0   1   1  59.172  57.976   4.719  o  1
        0   1   2  89.694  94.741   4.325  o  1
        0   1   3  51.743  52.241   3.850  o  1
        0   1   4   9.294  10.318   2.346  o  1
        0   1   5  41.160  39.951   3.313  o  1
        0   1   6   6.755   7.102    .895  <  1
        0   1   7  30.693  31.171   2.668  o  1
        0   1   8  12.324  12.085   2.391  o  1
        0   1   9  15.348  15.122   2.239  o  1
        0   1  10  17.622  19.605   1.997  o  1
;
  
;
Example 2 - based on standard test data set p6122 of the Xtal distribution
                [Hall, King & Stewart (1995). Xtal3.4 User's Manual. Univ.
                Western Australia].
;
 

 loop_
   _category_mandatory.name                                                   
  '_refln_index_l'
  '_refln_index_k'
  '_refln_index_h'

_database_code_depnum_ccdc_fiz
_category  database 
_definition
 
;
Deposition numbers assigned by the Fachinformatsionszentrum
               Karlsruhe (FIZ) to files containing structural information
               archived by the Cambridge Crystallographic Data Centre (CCDC).
;

_list  no 
_name '_database_code_depnum_ccdc_fiz'
_type  char 
_type_conditions  none 

_diffrn_measurement_device_details
_category 'diffrn_measurement'
_definition
 
;
A description of special aspects of the device used to measure
               the diffraction intensities.
;

_example
 
;
commercial goniometer modified locally to
                                 allow for 90\% \t arc
;

_list  no 
_name '_diffrn_measurement_device_details'
_type  char 
_type_conditions  none 

_chemical_formula_weight_meas
_category 'chemical_formula'
_definition
 'Formula mass in daltons measured by a non-diffraction experiment.'
_enumeration_range  1.0: 
_list  no 
_name '_chemical_formula_weight_meas'
_type  numb 
_type_conditions  none 
_units  Da 
_units_detail  daltons 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   1.0 
   1.0   1.0 

_diffrn_refln_sint/lambda
_category 'diffrn_refln'
_definition
 
;
The (sin theta)/lambda value in reciprocal angstroms for
               this reflection.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_sint/lambda'
_type  numb 
_type_conditions  none 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_melting_point
_category  chemical 
_definition
 
;
The temperature in kelvins at which a crystalline solid changes
               to a liquid.
;

_enumeration_range  0.0: 
_list  no 
_name '_chemical_melting_point'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_standards_interval_time
_category 'diffrn_standards'
_definition
 
;
The number of reflection intensities, or the time in minutes,
               between the measurement of standard reflection intensities.
;

_enumeration_range  0: 
_list  no 
_name '_diffrn_standards_interval_time'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_angle_phi
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_phi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_refln_wavelength
_category  refln 
_definition
 
;
The mean wavelength in angstroms of radiation used to measure
               this reflection. This is an important parameter for data
               collected using energy-dispersive detectors or the Laue method.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_wavelength'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_contact_[]
_category 'category_overview'
_category.id 'geom_contact'
_definition
 
;
Data items in the GEOM_CONTACT category record details about
               interatomic contacts, as calculated from the contents of the
               ATOM, CELL, and SYMMETRY data.
;

_list  no 
_name '_geom_contact_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
     _geom_contact_atom_site_label_1
     _geom_contact_atom_site_label_2
     _geom_contact_distance
     _geom_contact_site_symmetry_1
     _geom_contact_site_symmetry_2
     _geom_contact_publ_flag
     O(1)  O(2)     2.735(3)  .  .  yes
     H(O1) O(2)     1.82      .  .  no
;
  
;
Example 1 - based on data set CLPHO6 of Ferguson, Ruhl, McKervey & Browne
                [(1991). Acta Cryst. C48, 2262-2264].
;
 

 loop_
   _category_mandatory.name                                                   
  '_geom_contact_atom_site_label_1'
  '_geom_contact_atom_site_label_2'

_geom_hbond_atom_site_label_H
_category 'geom_hbond'
_definition
 
;
The labels of three atom sites (respectively the donor, hydrogen
               atom and acceptor atom) participating in a hydrogen bond. These
               must match labels specified as _atom_site_label in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_hbond_atom_site_label_H'
_type  char 
_type_conditions  none 

_atom_type_analytical_mass_%
_category 'atom_type'
_definition
 'Mass percentage of this atom type derived from chemical analysis.'
_enumeration_range  0.0:100.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_analytical_mass_%'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   100.0   100.0 
   100.0   0.0 
   0.0   0.0 

_geom_hbond_atom_site_label_A
_category 'geom_hbond'
_definition
 
;
The labels of three atom sites (respectively the donor, hydrogen
               atom and acceptor atom) participating in a hydrogen bond. These
               must match labels specified as _atom_site_label in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_hbond_atom_site_label_A'
_type  char 
_type_conditions  none 

_valence_param_atom_2_valence
_category 'valence_param'
_definition
 
;
The valence (formal charge) of the second atom whose bond
               valence parameters are given in this category.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_atom_2_valence'
_type  numb 
_type_conditions  none 

_geom_hbond_atom_site_label_D
_category 'geom_hbond'
_definition
 
;
The labels of three atom sites (respectively the donor, hydrogen
               atom and acceptor atom) participating in a hydrogen bond. These
               must match labels specified as _atom_site_label in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_hbond_atom_site_label_D'
_type  char 
_type_conditions  none 

_diffrn_radiation_detector_dtime
_category 'diffrn_detector'
_definition
 
;
The deadtime in microseconds of the detector used to measure
               the diffraction intensities.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_radiation_detector_dtime'
_related_function  replace 
_related_item '_diffrn_detector_dtime'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_ambient_environment
_category  diffrn 
_definition 'The gas or liquid surrounding the sample, if not air.'
_list  no 
_name '_diffrn_ambient_environment'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   He 
   vacuum 
  'mother liquor'

_diffrn_reflns_limit_l_min
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_l_min'
_type  numb 
_type_conditions  none 

_audit_conform_dict_name
_category 'audit_conform'
_definition
 
;
The string identifying the highest-level dictionary defining
               datanames used in this file.
;

_list  both 
_list_mandatory  yes 
_name '_audit_conform_dict_name'
_type  char 
_type_conditions  none 

_atom_site_label
_category 'atom_site'
_definition
 
;
The _atom_site_label is a unique identifier for a particular site
               in the crystal. This code is made up of a sequence of up to seven
               components, _atom_site_label_component_0 to *_6, which may be
               specified as separate data items. Component 0 usually matches one
               of the specified _atom_type_symbol codes. This is not mandatory
               if an _atom_site_type_symbol item is included in the atom site
               list. The _atom_site_type_symbol always takes precedence over
               an _atom_site_label in the identification of the atom type. The
               label components 1 to 6 are optional, and normally only
               components 0 and 1 are used. Note that components 0 and 1 are
               concatenated, while all other components, if specified, are
               separated by an underline character. Underline separators are
               only used if higher-order components exist. If an intermediate
               component is not used it may be omitted provided the underline
               separators are inserted. For example the label 'C233__ggg' is
               acceptable and represents the components C, 233, '', and ggg.
               Each label may have a different number of components.
;

_list  yes 
_list_mandatory  yes 
_name '_atom_site_label'
_type  char 
_type_conditions  none 

 loop_
   _list_link_child                                                           
  '_atom_site_aniso_label'
  '_geom_angle_atom_site_label_1'
  '_geom_angle_atom_site_label_2'
  '_geom_angle_atom_site_label_3'
  '_geom_bond_atom_site_label_1'
  '_geom_bond_atom_site_label_2'
  '_geom_contact_atom_site_label_1'
  '_geom_contact_atom_site_label_2'
  '_geom_hbond_atom_site_label_D'
  '_geom_hbond_atom_site_label_H'
  '_geom_hbond_atom_site_label_A'
  '_geom_torsion_atom_site_label_1'
  '_geom_torsion_atom_site_label_2'
  '_geom_torsion_atom_site_label_3'
  '_geom_torsion_atom_site_label_4'

 loop_
   _example                                                                   
   C12 
   Ca3g28 
   Fe3+17 
   H*251 
   boron2a 
  'C_a_phe_83_a_0'
  'Zn_Zn_301_A_0'

_diffrn_standards_scale_u
_category 'diffrn_standards'
_definition
 
;
The standard uncertainty of the individual mean
               standard scales applied to the intensity data.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_standards_scale_u'
_related_function  alternate 
_related_item '_diffrn_standards_scale_sigma'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_date_to_coeditor
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_to_coeditor'
_type  char 
_type_conditions  none 

_refine_ls_structure_factor_coef
_category  refine 
_definition
 
;
Structure-factor coefficient |F|, F^2^ or I, used in the
               least-squares refinement process.
;

_enumeration_default  F 
_list  no 
_name '_refine_ls_structure_factor_coef'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   F  'structure factor magnitude'
   Fsqd  'structure factor squared'
   Inet  'net intensity'

_reflns_shell_number_measured_all
_category 'reflns_shell'
_definition
 
;
The total number of reflections measured for this
               resolution shell.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_number_measured_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_restraints
_category 'atom_site'
_definition
 
;
A description of restraints applied to specific parameters at
               this site during refinement. See also _atom_site_refinement_flags
               and _refine_ls_number_restraints.
;

_example 'restrained to planar ring'
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_restraints'
_type  char 
_type_conditions  none 

_reflns_scale_meas_intensity
_category 'reflns_scale'
_definition 'Scales associated with _reflns_scale_group_code.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_scale_group_code'
_name '_reflns_scale_meas_intensity'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_source
_category 'diffrn_source'
_definition 'The general class of the source of radiation.'
_list  no 
_name '_diffrn_source'
_related_function  alternate 
_related_item '_diffrn_radiation_source'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'sealed X-ray tube'
  'nuclear reactor'
  'spallation source'
  'electron microscope'
  'rotating-anode X-ray tube'
   synchrotron 

_geom_torsion_site_symmetry_2
_category 'geom_torsion'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion_site_symmetry_2'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_citation_year
_category  citation 
_definition
 
;
The year of the citation;  relevant for both journal articles
               and book chapters.
;

_example  1984 
_list  yes 
_list_reference '_citation_id'
_name '_citation_year'
_type  numb 
_type_conditions  none 

_diffrn_refln_intensity_u
_category 'diffrn_refln'
_definition
 
;
Standard uncertainty of the net intensity calculated from
               the diffraction counts after the attenuator and standard
               scales have been applied.
;

_enumeration_range  0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_intensity_u'
_related_function  alternate 
_related_item '_diffrn_refln_intensity_sigma'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_techeditor_fax
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_fax'
_type  char 
_type_conditions  none 

_refine_ls_weighting_details
_category  refine 
_definition
 
;
A description of special aspects of the weighting scheme used
               in least-squares refinement. Used to describe the weighting
               when the value of _refine_ls_weighting_scheme is specified
               as 'calc'.
;

_example
 
;
Sigdel model of Konnert-Hendrickson:
                   Sigdel = Afsig +  Bfsig*(sin(\q)/\l - 1/6)
                   Afsig = 22.0, Bfsig = 150.0 at the beginning of refinement.
                   Afsig = 16.0, Bfsig =  60.0 at the end of refinement.
;

_list  no 
_name '_refine_ls_weighting_details'
_type  char 
_type_conditions  none 

_diffrn_ambient_temperature
_category  diffrn 
_definition
 
;
The mean temperature in kelvins at which the intensities
              were measured.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_temperature'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_radiation_filter_edge
_category 'diffrn_radiation'
_definition 'Absorption edge in angstroms of the radiation filter used.'
_enumeration_range  0.0: 
_list  no 
_name '_diffrn_radiation_filter_edge'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_number_reflns
_category  refine 
_definition
 
;
The number of unique reflections contributing to the
               least-squares refinement calculation.
;

_enumeration_range  0: 
_list  no 
_name '_refine_ls_number_reflns'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_orient_refln_index_l
_category 'diffrn_orient_refln'
_definition
 
;
The indices of a reflection used to define the orientation
               matrix. See _diffrn_orient_matrix_.
;

_list  yes 
_list_mandatory  yes 
_name '_diffrn_orient_refln_index_l'
_type  numb 
_type_conditions  none 

_diffrn_detector_dtime
_category 'diffrn_detector'
_definition
 
;
The deadtime in microseconds of the detector used to measure
               the diffraction intensities.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_detector_dtime'
_related_function  alternate 
_related_item '_diffrn_radiation_detector_dtime'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_ambient_temperature_lt
_category  diffrn 
_definition
 
;
The mean temperature in kelvins above which (*_gt) or below
              which (*_lt) the intensities were measured.  These items allow
              a range of temperatures to be given. 

              _diffrn_ambient_temperature should always be used in preference
              to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_temperature_lt'
_related_function  alternate 
_related_item '_diffrn_ambient_temperature'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_techeditor_address
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_address'
_type  char 
_type_conditions  none 

_chemical_absolute_configuration
_category  chemical 
_definition
 
;
Necessary conditions for the assignment of
               _chemical_absolute_configuration are given by H. D. Flack and
               G. Bernardinelli (1999, 2000).

               Ref: Flack, H. D. & Bernardinelli, G. (1999). Acta Cryst. A55,
                       908-915. (http://www.iucr.org/paper?sh0129)
                    Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst.
                       33, 1143-1148. (http://www.iucr.org/paper?ks0021)
;

_list  no 
_name '_chemical_absolute_configuration'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   rm  
;
absolute configuration established by
                                         the structure determination of a
                                         compound containing a chiral reference
                                         molecule of known absolute
                                         configuration
;
 
   ad  
;
absolute configuration established by
                                         anomalous dispersion effects in
                                         diffraction measurements on the
                                         crystal
;
 
   rmad  
;
absolute configuration established by
                                         the structure determination of a
                                         compound containing a chiral reference
                                         molecule of known absolute
                                         configuration and confirmed by
                                         anomalous dispersion effects in
                                         diffraction measurements on the
                                         crystal
;
 
   syn  
;
absolute configuration has not been
                                         established by anomalous dispersion
                                         effects in diffraction measurements on
                                         the crystal. The enantiomer has been
                                         assigned by reference to an unchanging
                                         chiral centre in the synthetic
                                         procedure
;
 
   unk  
;
absolute configuration is unknown,
                                         there being no firm chemical evidence
                                         for its assignment to hand and it
                                         having not been established by
                                         anomalous dispersion effects in
                                         diffraction measurements on the
                                         crystal. An arbitrary choice of
                                         enantiomer has been made
;
 
   .   inapplicable 

_refine_ls_R_factor_gt
_category  refine 
_definition
 
;
Residual factor for the reflections (with number given by
               _reflns_number_gt) judged significantly intense (i.e. satisfying
               the threshold specified by _reflns_threshold_expression)
               and included in the refinement. The reflections also satisfy
               the resolution limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_R_factor_gt'
_related_function  alternate 
_related_item '_refine_ls_R_factor_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_shift/su_mean
_category  refine 
_definition
 
;
The average ratio of the final least-squares parameter
               shift divided by the final standard uncertainty.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/su_mean'
_related_function  alternate 
_related_item '_refine_ls_shift/esd_mean'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_number_observed
_category  reflns 
_definition
 
;
The number of 'observed' reflections, in the _refln_ list (not
               the _diffrn_refln_ list). The observed reflections satisfy the
               threshold criterion specified by _reflns_threshold_expression
               (or the deprecated _reflns_observed_criterion). They may include
               Friedel equivalent reflections according to the nature of the
               structure and the procedures used. The special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details.
;

_enumeration_range  0: 
_list  no 
_name '_reflns_number_observed'
_related_function  replace 
_related_item '_reflns_number_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refln_A_meas
_category  refln 
_definition
 
;
The calculated and measured structure-factor component A
               (in electrons for X-ray diffraction).

               A =|F|cos(phase)
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_A_meas'
_type  numb 
_type_conditions  none 

_atom_sites_fract_tran_matrix_32
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_32'
_type  numb 
_type_conditions  none 

_diffrn_refln_scale_group_code
_category 'diffrn_refln'
_definition
 
;
The code identifying the scale applying to this reflection. This
               code must match with a specified _diffrn_scale_group_code value.
;

_list  yes 
_list_link_parent '_diffrn_scale_group_code'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scale_group_code'
_type  char 
_type_conditions  none 

_cell_measurement_refln_theta
_category 'cell_measurement_refln'
_definition
 
;
Theta angle in degrees for the reflection used for
               measurement of the unit cell with the indices
               _cell_measurement_refln_index_.
;

_enumeration_range  0.0:90.0 
_list  yes 
_list_reference '_cell_measurement_refln_index_'
_name '_cell_measurement_refln_theta'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_atom_sites_fract_tran_matrix_31
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_31'
_type  numb 
_type_conditions  none 

_exptl_crystal_face_diffr_kappa
_category 'exptl_crystal_face'
_definition
 
;
The goniometer angle settings in degrees when the perpendicular
               to the specified crystal face is aligned along a specified
               direction (e.g. the bisector of the incident and reflected beams
               in an optical goniometer).

;

_list  yes 
_list_reference '_exptl_crystal_face_index_'
_name '_exptl_crystal_face_diffr_kappa'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_journal_date_proofs_out
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_proofs_out'
_type  char 
_type_conditions  none 

_audit_contact_author_fax
_category 'audit_contact_author'
_definition
 
;
The facsimile telephone number of the author of the data
               block to whom correspondence should be addressed.

               The recommended style includes the international dialing
               prefix, the area code in parentheses, followed by the
               local number with no spaces.
;

_list  no 
_name '_audit_contact_author_fax'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   12(34)9477334 
   12()349477334 

_audit_creation_method
_category  audit 
_definition 'A description of how data were entered into the data block.'
_example 'spawned by the program QBEE'
_list  no 
_name '_audit_creation_method'
_type  char 
_type_conditions  none 

_atom_sites_solution_secondary
_category 'atom_sites'
_definition
 
;
Codes which identify the methods used to locate the initial
               atomic sites. The *_primary code identifies how the first
               atom sites were determined; the *_secondary code identifies
               how the remaining non-hydrogen sites were located; and the
               *_hydrogens code identifies how the hydrogens were located.
;

_list  no 
_name '_atom_sites_solution_secondary'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   difmap  'difference Fourier map'
   vecmap  'real-space vector search'
   heavy  'heavy-atom method'
   direct  'structure-invariant direct methods'
   geom  'inferred from neighbouring sites'
   disper  'anomalous-dispersion techniques'
   isomor  'isomorphous structure methods'

_reflns_shell_number_unique_all
_category 'reflns_shell'
_definition
 
;
The total number of measured reflections resulting from
               merging measured symmetry-equivalent reflections for this
               resolution shell.
;

_enumeration_range  0: 
_list  yes 
_name '_reflns_shell_number_unique_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_av_R_equivalents
_category 'diffrn_reflns'
_definition
 
;
The residual [sum av|del(I)| / sum |av(I)|] for
               symmetry-equivalent reflections used to calculate the
               average intensity av(I). The av|del(I)| term is the
               average absolute difference between av(I) and the
               individual symmetry-equivalent intensities.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_reflns_av_R_equivalents'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_book_id_ISBN
_category  citation 
_definition
 
;
The International Standard Book Number (ISBN) code assigned to
               the book cited;  relevant for book chapters.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_book_id_ISBN'
_type  char 
_type_conditions  none 

_diffrn_reflns_transf_matrix_12
_category 'diffrn_reflns'
_definition
 
;
Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;

_list  no 
_name '_diffrn_reflns_transf_matrix_12'
_type  numb 
_type_conditions  none 

_geom_bond_atom_site_label_1
_category 'geom_bond'
_definition
 
;
The labels of two atom sites that form a bond. These must match
               labels specified as _atom_site_label in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_bond_atom_site_label_1'
_type  char 
_type_conditions  none 

_geom_bond_atom_site_label_2
_category 'geom_bond'
_definition
 
;
The labels of two atom sites that form a bond. These must match
               labels specified as _atom_site_label in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_bond_atom_site_label_2'
_type  char 
_type_conditions  none 

_diffrn_refln_counts_total
_category 'diffrn_refln'
_definition
 
;
The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_counts_total'
_type  numb 
_type_conditions  none 

_citation_journal_id_ASTM
_category  citation 
_definition
 
;
The American Society for the Testing of Materials (ASTM) code
               assigned to the journal cited (also referred to as the CODEN
               designator of the Chemical Abstracts Service); relevant for
               journal articles.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_id_ASTM'
_type  char 
_type_conditions  none 

_atom_site_label_component_1
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_1'
_type  char 
_type_conditions  none 

_diffrn_reflns_theta_min
_category 'diffrn_reflns'
_definition 'Minimum theta angle in degrees for the measured intensities.'
_enumeration_range  0.0:90.0 
_list  no 
_name '_diffrn_reflns_theta_min'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_atom_type_radius_bond
_category 'atom_type'
_definition
 
;
The effective intra- and intermolecular bonding radii in
               angstroms of this atom type.
;

_enumeration_range  0.0:5.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_radius_bond'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   5.0   5.0 
   5.0   0.0 
   0.0   0.0 

_exptl_crystal_preparation
_category 'exptl_crystal'
_definition
 
;
Details of crystal growth and preparation of the crystal (e.g.
               mounting) prior to the intensity measurements.
;

_example 'mounted in an argon-filled quartz capillary'
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_preparation'
_type  char 
_type_conditions  none 

_reflns_d_resolution_low
_category  reflns 
_definition
 
;
The highest and lowest resolution in angstroms for the
               interplanar spacings in the reflections. These are the
               smallest and largest d values.
;

_enumeration_range  0.0: 
_list  no 
_name '_reflns_d_resolution_low'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_torsion_site_symmetry_1
_category 'geom_torsion'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion_site_symmetry_1'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_audit_author_[]
_category 'category_overview'
_category.id 'audit_author'
_definition
 
;
Data items in the AUDIT_AUTHOR category record details about
               the author(s) of the data block.
;

_list  no 
_name '_audit_author_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _audit_author_name
    _audit_author_address
        'Fitzgerald, Paula M. D.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
        'Van Middlesworth, J. F.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

 loop_
   _category_mandatory.name                                                   
  '_audit_author_name'

_database_journal_ASTM
_category  database 
_definition
 
;
The ASTM CODEN designator for a journal as given in the
               Chemical Source List maintained by the Chemical Abstracts
               Service, and the journal code used in the Cambridge Structural
               Database.
;

_list  no 
_name '_database_journal_ASTM'
_type  char 
_type_conditions  none 

_atom_site_label_component_4
_category 'atom_site'
_definition
 
;
Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underline.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_label_component_4'
_type  char 
_type_conditions  none 

_diffrn_refln_angle_theta
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_theta'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_citation_page_first
_category  citation 
_definition
 
;
The first and last pages of the citation;  relevant for both
               journal articles and book chapters.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_page_first'
_type  char 
_type_conditions  none 

_journal_page_last
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_page_last'
_type  char 
_type_conditions  none 

_diffrn_reflns_limit_k_min
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_k_min'
_type  numb 
_type_conditions  none 

_diffrn_radiation_monochromator
_category 'diffrn_radiation'
_definition
 
;
The method used to obtain monochromatic radiation. If a mono-
               chromator crystal is used the material and the indices of the
               Bragg reflection are specified.
;

_list  no 
_name '_diffrn_radiation_monochromator'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Zr filter'
  'Ge 220'
   none 
  'equatorial mounted graphite'

_publ_contact_author_id_iucr
_category  publ 
_definition
 
;
Identifier in the IUCr contact database of the author
               submitting the manuscript and datablock. This identifier may
               be available from the World Directory of Crystallographers
               (http://wdc.iucr.org).
;

_example  2985 
_list  no 
_name '_publ_contact_author_id_iucr'
_type  char 
_type_conditions  none 

_audit_block_code
_category  audit 
_definition 'A code intended to identify uniquely the current data block.'
_example 'TOZ_1991-03-20'
_list  no 
_name '_audit_block_code'
_type  char 
_type_conditions  none 

_citation_author_citation_id
_category 'citation_author'
_definition
 
;
The value of _citation_author_citation_id must match an
               identifier specified by _citation_id in the _citation_ list.
;

_list  yes 
_list_link_parent '_citation_id'
_list_mandatory  yes 
_name '_citation_author_citation_id'
_type  char 
_type_conditions  none 

_atom_site_fract_x
_category 'atom_site'
_definition 'Atom site coordinates as fractions of the _cell_length_ values.'
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_fract_x'
_related_function  alternate 
_related_item '_atom_site_Cartn_'
_type  numb 
_type_conditions  esd 

_atom_site_fract_y
_category 'atom_site'
_definition 'Atom site coordinates as fractions of the _cell_length_ values.'
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_fract_y'
_related_function  alternate 
_related_item '_atom_site_Cartn_'
_type  numb 
_type_conditions  esd 

_atom_site_fract_z
_category 'atom_site'
_definition 'Atom site coordinates as fractions of the _cell_length_ values.'
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_fract_z'
_related_function  alternate 
_related_item '_atom_site_Cartn_'
_type  numb 
_type_conditions  esd 

_diffrn_detector_area_resol_mean
_category 'diffrn_detector'
_definition 'The resolution of an area detector, in pixels/mm.'
_enumeration_range  0.0: 
_list  no 
_name '_diffrn_detector_area_resol_mean'
_type  numb 
_type_conditions  none 
_units  mm^-1^ 
_units_detail 'pixels per millimetre'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_type_radius_contact
_category 'atom_type'
_definition
 
;
The effective intra- and intermolecular bonding radii in
               angstroms of this atom type.
;

_enumeration_range  0.0:5.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_radius_contact'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   5.0   5.0 
   5.0   0.0 
   0.0   0.0 

_diffrn_refln_scan_mode_backgd
_category 'diffrn_refln'
_definition
 
;
The code identifying the mode of scanning a reflection to measure
               the background intensity.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scan_mode_backgd'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   st  'stationary counter background'
   mo  'moving counter background'

_diffrn_reflns_resolution_max
_category 'diffrn_reflns'
_definition
 
;
Maximum resolution in reciprocal angstroms of the measured
               diffraction pattern.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_reflns_resolution_max'
_related_function  alternate 
_related_item '_diffrn_reflns_theta_max'
_type  numb 
_type_conditions  none 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_space_group_symop_sg_id
_category 'space_group_symop'
_definition
 
;
This must match a particular value of _space_group_id allowing
               the symmetry operation to be identified with a particular space
               group.
;

_list  both 
_list_link_parent '_space_group_id'
_list_mandatory  no 
_list_reference '_space_group_symop_id'
_name '_space_group_symop_sg_id'
_type  numb 
_type_conditions  none 

_journal_date_recd_copyright
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_recd_copyright'
_type  char 
_type_conditions  none 

_refine_diff_density_min
_category  refine 
_definition
 
;
The largest, smallest and root-mean-square-deviation, in
               electrons per angstrom cubed, of the final difference electron
               density. The *_rms value is measured with
               respect to the arithmetic mean density, and is derived from
               summations over each grid point in the asymmetric unit of
               the cell. This quantity is useful for assessing the
               significance of *_min and *_max values, and also for
               defining suitable contour levels.
;

_list  no 
_name '_refine_diff_density_min'
_type  numb 
_type_conditions  esd 
_units 'e_A^-3^'
_units_detail 'electrons per cubic angstrom'

_journal_date_from_coeditor
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_from_coeditor'
_type  char 
_type_conditions  none 

_chemical_temperature_sublimation
_category  chemical 
_definition 'The temperature in kelvins at which a solid sublimes. '
_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_sublimation'
_type  numb 
_type_conditions  esd 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_journal_techeditor_email
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_email'
_type  char 
_type_conditions  none 

_publ_body_[]
_category 'category_overview'
_category.id 'publ_body'
_definition
 
;
Data items in the PUBL_BODY category permit labelling of
               different text sections within the body of a submitted paper.
               Note that these should not be used in a paper which has
               a standard format with sections tagged by specific data names
               (such as in Acta Crystallographica Section C). Typically,
               each journal will supply a list of the specific items it
               requires in its Notes for Authors.
;

_list  no 
_name '_publ_body_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _publ_body_element
    _publ_body_label
    _publ_body_title
    _publ_body_format
    _publ_body_contents

         section   1         Introduction                                cif
    ; X-ray diffraction from a crystalline material provides
      information on the thermally and spatially averaged
      electron density in the crystal...
    ;
         section   2         Theory                                      tex
    ; In the rigid-atom approximation, the dynamic electron
      density of an atom is described by the convolution
      product of the static atomic density and a probability
      density function,
            $\rho_{dyn}(\bf r) = \rho_{stat}(\bf r) * P(\bf r).  \eqno(1) $
    ;
;
  
;
Example 1 - based on a paper by R. Restori & D. Schwarzenbach (1996),
                Acta Cryst. A52, 369-378.
;
 
  
;
loop_
    _publ_body_element
    _publ_body_label
    _publ_body_title
    _publ_body_contents

         section        3
    ; The two-channel method for retrieval of the deformation
      electron density
    ;
         .
         subsection     3.1    'The two-channel entropy S[\D\r(r)]'
    ; As the wide dynamic range involved in the total electron density...
    ;
         subsection     3.2
    'Uniform vs informative prior model densities'        .
         subsubsection  3.2.1  'Use of uniform models'
    ; Straightforward algebra leads to expressions analogous to...
    ;
;
  
;
Example 2 - based on a paper by R. J. Papoular, Y. Vekhter & P. Coppens
                (1996), Acta Cryst. A52, 397-407.
;
 

 loop_
   _category_mandatory.name                                                   
  '_publ_body_label'

 loop_
   _category_key.name                                                         
  '_publ_body_label'
  '_publ_body_element'

_diffrn_measured_fraction_theta_max
_category  diffrn 
_definition
 
;
Fraction of unique (symmetry-independent) reflections measured
          out to _diffrn_reflns_theta_max.
;

_enumeration_range  0:1.0 
_list  yes 
_name '_diffrn_measured_fraction_theta_max'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_journal_suppl_publ_pages
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_suppl_publ_pages'
_type  char 
_type_conditions  none 

_geom_contact_publ_flag
_category 'geom_contact'
_definition
 
;
This code signals if the contact distance is referred to in a
               publication or should be placed in a list of significant contact
               distances.
;

_enumeration_default  no 
_list  yes 
_list_reference '_geom_contact_atom_site_label_'
_name '_geom_contact_publ_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'do not include distance in special list'
   n  'abbreviation for "no"'
   yes  'do include distance in special list'
   y  'abbreviation for "yes"'

_audit_creation_date
_category  audit 
_definition
 
;
A date that the data block was created. The date format
               is yyyy-mm-dd.
;

_example  1990-07-12 
_list  no 
_name '_audit_creation_date'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_32
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_32'
_type  numb 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_33
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_33'
_type  numb 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_31
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_31'
_type  numb 
_type_conditions  none 

_reflns_class_R_factor_gt
_category 'reflns_class'
_definition
 
;
For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _reflns_class_d_res_high and _reflns_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _reflns_class_wR_factor_all definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_R_factor_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_torsion
_category 'geom_torsion'
_definition
 
;
The torsion angle in degrees bounded by the four atom sites
               identified by the _geom_torsion_atom_site_label_ codes. These
               must match labels specified as _atom_site_label in the atom list.
               The torsion angle definition should be that of Klyne and Prelog.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

_atom_type_scat_Cromer_Mann_c
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_c'
_type  numb 
_type_conditions  none 

_refln_include_status
_category  refln 
_definition
 
;
Classification of a reflection so as to indicate its status with
               respect to inclusion in refinement and calculation of R factors.
;

_enumeration_default  o 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_include_status'
_related_function  alternate 
_related_item '_refln_observed_status'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   o  
;
(lower-case letter o for 'observed')
                                      satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      exceeds _reflns_threshold_expression
;
 
   <  
;
satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      does not exceed
                                        _reflns_threshold_expression
;
 
   -  'systematically absent reflection'
   x  'unreliable measurement -- not used'
   h  'does not satisfy _refine_ls_d_res_high'
   l  'does not satisfy _refine_ls_d_res_low'

_diffrn_reflns_resolution_full
_category 'diffrn_reflns'
_definition
 
;
The resolution in reciprocal angstroms at which the measured 
               reflection count is close to complete.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_reflns_resolution_full'
_related_function  alternate 
_related_item '_diffrn_reflns_theta_full'
_type  numb 
_type_conditions  none 
_units  A^-1^ 
_units_detail 'reciprocal angstroms'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_code_CSD
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_CSD'
_type  char 
_type_conditions  none 

_diffrn_standards_number
_category 'diffrn_standards'
_definition
 
;
The number of unique standard reflections used in the diffraction
               measurements.
;

_enumeration_range  0: 
_list  no 
_name '_diffrn_standards_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_attenuator_material
_category 'diffrn_attenuator'
_definition 'Material from which the attenuator is made.'
_list  yes 
_list_reference '_diffrn_attenuator_code'
_name '_diffrn_attenuator_material'
_type  char 
_type_conditions  none 

_refine_ls_wR_factor_all
_category  refine 
_definition
 
;
Weighted residual factors for all reflections.
               The reflections also satisfy the resolution limits established
               by _refine_ls_d_res_high and _refine_ls_d_res_low.
               See also the _refine_ls_R_factor_ definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_wR_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_symmetry_Int_Tables_number
_category  symmetry 
_definition
 
;
Space-group number from International Tables for Crystallography,
               Vol. A (1987).
;

_enumeration_range  1:230 
_list  no 
_name '_symmetry_Int_Tables_number'
_related_function  replace 
_related_item '_space_group_IT_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   230.0   230.0 
   230.0   1.0 
   1.0   1.0 

_diffrn_reflns_class_av_sgI/I
_category 'diffrn_reflns_class'
_definition
 
;
Measure [sum|u(net I)|/sum|net I|] for all measured intensities
               in a reflection class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_reflns_class_code'
_name '_diffrn_reflns_class_av_sgI/I'
_related_function  replace 
_related_item '_diffrn_reflns_class_av_uI/I'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_source_target
_category 'diffrn_source'
_definition
 
;
The chemical element symbol for the X-ray target
               (usually the anode) used for generation of X-rays.
               This can be used also for spallation sources.
;

_list  no 
_name '_diffrn_source_target'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   H 
   He 
   Li 
   Be 
   B 
   C 
   N 
   O 
   F 
   Ne 
   Na 
   Mg 
   Al 
   Si 
   P 
   S 
   Cl 
   Ar 
   K 
   Ca 
   Sc 
   Ti 
   V 
   Cr 
   Mn 
   Fe 
   Co 
   Ni 
   Cu 
   Zn 
   Ga 
   Ge 
   As 
   Se 
   Br 
   Kr 
   Rb 
   Sr 
   Y 
   Zr 
   Nb 
   Mo 
   Tc 
   Ru 
   Rh 
   Pd 
   Ag 
   Cd 
   In 
   Sn 
   Sb 
   Te 
   I 
   Xe 
   Cs 
   Ba 
   La 
   Ce 
   Pr 
   Nd 
   Pm 
   Sm 
   Eu 
   Gd 
   Tb 
   Dy 
   Ho 
   Er 
   Tm 
   Yb 
   Lu 
   Hf 
   Ta 
   W 
   Re 
   Os 
   Ir 
   Pt 
   Au 
   Hg 
   Tl 
   Pb 
   Bi 
   Po 
   At 
   Rn 
   Fr 
   Ra 
   Ac 
   Th 
   Pa 
   U 
   Np 
   Pu 
   Am 
   Cm 
   Bk 
   Cf 
   Es 
   Fm 
   Md 
   No 
   Lr 

_refine_ls_abs_structure_Rogers
_category  refine 
_definition
 
;
The measure of absolute structure as defined by Rogers.

               The value must lie in the 99.97% Gaussian confidence interval
               -1 -3u =< \h =< 1 + 3u and a standard uncertainty (e.s.d.) u must
               be supplied. The _enumeration_range of -1.0:1.0 is correctly
               interpreted as meaning (-1.0 - 3u) =< \h =< (1.0 + 3u).

               Ref: Rogers, D. (1981). Acta Cryst. A37, 734-741.
;

_enumeration_range  -1.0:1.0 
_list  no 
_name '_refine_ls_abs_structure_Rogers'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   -1.0 
   -1.0   -1.0 

_citation_author_name
_category 'citation_author'
_definition
 
;
Name of an author of the citation; relevant for both journal
               articles and book chapters.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

_list  yes 
_list_mandatory  yes 
_name '_citation_author_name'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'Bleary, Percival R.'
  "O'Neil, F.K."
  'Van den Bossche, G.'
  'Yang, D.-L.'
  'Simonov, Yu.A'
  'M\"uller, H.A.'
  'Ross II, C.R.'

_refine_ls_number_restraints
_category  refine 
_definition
 
;
The number of restrained parameters. These are parameters which
               are not directly dependent on another refined parameter. Often
               restrained parameters involve geometry or energy dependencies.
               See also _atom_site_constraints and _atom_site_refinement_flags.
               A general description of refinement constraints may appear in
               _refine_special_details.
;

_enumeration_range  0: 
_list  no 
_name '_refine_ls_number_restraints'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_number_constraints
_category  refine 
_definition
 
;
The number of constrained (non-refined or dependent) parameters
               in the least-squares process. These may be due to symmetry or any
               other constraint process (e.g. rigid-body refinement). See also
               _atom_site_constraints and _atom_site_refinement_flags. A general
               description of constraints may appear in _refine_special_details.
;

_enumeration_default  0 
_enumeration_range  0: 
_list  no 
_name '_refine_ls_number_constraints'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_standard_refln_[]
_category 'category_overview'
_category.id 'diffrn_standard_refln'
_definition
 
;
Data items in the DIFFRN_STANDARD_REFLN category record details
               about the reflections treated as standards during the measurement
               of diffraction intensities.

               Note that these are the individual standard reflections, not the
               results of the analysis of the standard reflections.
;

_list  no 
_name '_diffrn_standard_refln_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _diffrn_standard_refln_index_h
    _diffrn_standard_refln_index_k
    _diffrn_standard_refln_index_l
    3 2 4    1 9 1    3 0 10
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_diffrn_standard_refln_index_h'
  '_diffrn_standard_refln_index_k'
  '_diffrn_standard_refln_index_l'

_reflns_shell_Rmerge_F_gt
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(F) for significantly intense reflections
               (see _reflns_threshold_expression) in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_F_gt'
_related_function  alternate 
_related_item '_reflns_shell_Rmerge_F_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_radiation_source
_category 'diffrn_source'
_definition 'The source of radiation.'
_list  no 
_name '_diffrn_radiation_source'
_related_function  replace 
_related_item '_diffrn_source'
_type  char 
_type_conditions  none 

_atom_site_refinement_flags
_category 'atom_site'
_definition
 
;
A concatenated series of single-letter codes which indicate the
            refinement restraints or constraints applied to this site.  This
            item should not be used.  It has been replaced by
            _atom_site_refinement_flags_posn, *_adp and *_occupancy. It is
            retained in this dictionary only to provide compatibility with
            legacy CIFs.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_refinement_flags'
_type  char 
_type_conditions  none 

 loop_
   _related_function                                                          
   _related_item                                                              
   replace  '_atom_site_refinement_flags_posn'
   replace  '_atom_site_refinement_flags_adp'
   replace  '_atom_site_refinement_flags_occupancy'

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   .  'no refinement constraints'
   S  'special position constraint on site'
   G  'rigid group refinement of site'
   R  'riding-atom site attached to non-riding atom'
   D  'distance or angle restraint on site'
   T  'thermal displacement constraints'
   U  'Uiso or Uij restraint (rigid bond)'
   P  'partial occupancy constraint'

_journal_name_full
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_name_full'
_type  char 
_type_conditions  none 

_diffrn_refln_class_code
_category 'diffrn_refln'
_definition
 
;
The code identifying the class to which this reflection has
               been assigned. This code must match a value of
               _diffrn_reflns_class_code. Reflections may be grouped into
               classes for a variety of purposes. For example, for modulated
               structures each reflection class may be defined by the
               number m=sum|m~i~|, where the m~i~ are the integer coefficients
               that, in addition to h,k,l, index the corresponding diffraction
               vector in the basis defined for the reciprocal lattice.
;

_list  yes 
_list_link_parent '_diffrn_reflns_class_code'
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_class_code'
_type  char 
_type_conditions  none 

_diffrn_orient_refln_angle_theta
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_theta'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_diffrn_refln_counts_peak
_category 'diffrn_refln'
_definition
 
;
The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_counts_peak'
_type  numb 
_type_conditions  none 

_atom_site_thermal_displace_type
_category 'atom_site'
_definition
 
;
A standard code used to describe the type of atomic displacement
               parameters used for the site.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_thermal_displace_type'
_related_function  replace 
_related_item '_atom_site_adp_type'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   Uani  'anisotropic Uij'
   Uiso  'isotropic U'
   Uovl  'overall U'
   Umpe  'multipole expansion U'
   Bani  'anisotropic Bij'
   Biso  'isotropic B'
   Bovl  'overall B'

_citation_journal_id_ISSN
_category  citation 
_definition
 
;
The International Standard Serial Number (ISSN) code assigned to
               the journal cited;  relevant for journal articles.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_id_ISSN'
_type  char 
_type_conditions  none 

_valence_param_Ro
_category 'valence_param'
_definition
 
;
The bond valence parameter Ro used in the expression

                     s = exp[(Ro - R)/B]
           
               where s is the valence of a bond of length R.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_Ro'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  Angstrom 

_atom_type_scat_Cromer_Mann_a2
_category 'atom_type'
_definition
 
;
The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography, Vol. IV
                    (1974) Table 2.2B
               or   International Tables for Crystallography, Vol. C
                    (1991) Tables 6.1.1.4 and 6.1.1.5
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_Cromer_Mann_a2'
_type  numb 
_type_conditions  none 

_atom_type_scat_versus_stol_list
_category 'atom_type'
_definition
 
;
A table of scattering factors as a function of sin theta over
               lambda. This table should be well commented to indicate the
               items present. Regularly formatted lists are strongly
               recommended.
;

_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_versus_stol_list'
_type  char 
_type_conditions  none 

_reflns_scale_meas_F
_category 'reflns_scale'
_definition 'Scales associated with _reflns_scale_group_code.'
_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_scale_group_code'
_name '_reflns_scale_meas_F'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_aniso_type_symbol
_category 'atom_site'
_definition
 
;
This _atom_type_symbol code links the anisotropic atom
               parameters to the atom type data associated with this site and
               must match one of the _atom_type_symbol codes in this list.
;

_list  yes 
_list_link_parent '_atom_site_type_symbol'
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_type_symbol'
_type  char 
_type_conditions  none 

_chemical_name_structure_type
_category  chemical 
_definition
 
;
Commonly used structure-type name. Usually only applied to
               minerals or inorganic compounds.
;

_list  no 
_name '_chemical_name_structure_type'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   perovskite 
   sphalerite 
   A15 

_symmetry_[]
_category 'category_overview'
_category.id  symmetry 
_definition
 
;
Data items in the SYMMETRY category record details about the
               space-group symmetry.
;

_list  no 
_name '_symmetry_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_symmetry_cell_setting             orthorhombic
    _symmetry_space_group_name_H-M     'P 21 21 21'
    _symmetry_space_group_name_Hall    'P 2ac 2ab'
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_reflns_shell_d_res_high
_category 'reflns_shell'
_definition
 
;
The highest resolution in angstroms for the interplanar spacing
               in the reflections in this shell. This is the smallest d value.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_d_res_high'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_threshold_expression
_category  reflns 
_definition
 
;
The threshold, usually based on multiples of u(I), u(F^2^)
               or u(F), that serves to identify significantly intense
               reflections, the number of which is given by _reflns_number_gt.
               These reflections are used in the calculation of
               _refine_ls_R_factor_gt.
;

_example  I>2u(I) 
_list  no 
_name '_reflns_threshold_expression'
_related_function  alternate 
_related_item '_reflns_observed_criterion'
_type  char 
_type_conditions  none 

_citation_journal_full
_category  citation 
_definition 'Full name of the journal cited;  relevant for journal articles.'
_example 'Journal of Molecular Biology'
_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_full'
_type  char 
_type_conditions  none 

_diffrn_radiation_polarisn_norm
_category 'diffrn_radiation'
_definition
 
;
The angle in degrees, as viewed from the specimen, between the
               perpendicular component of the polarisation and the diffraction
               plane. See _diffrn_radiation_polarisn_ratio.
;

_enumeration_range  -180.0:180.0 
_list  no 
_name '_diffrn_radiation_polarisn_norm'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   -180.0 
   -180.0   -180.0 

_exptl_crystal_face_diffr_phi
_category 'exptl_crystal_face'
_definition
 
;
The goniometer angle settings in degrees when the perpendicular
               to the specified crystal face is aligned along a specified
               direction (e.g. the bisector of the incident and reflected beams
               in an optical goniometer).

;

_list  yes 
_list_reference '_exptl_crystal_face_index_'
_name '_exptl_crystal_face_diffr_phi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_database_code_CAS
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_CAS'
_type  char 
_type_conditions  none 

_publ_manuscript_incl_[]
_category 'category_overview'
_category.id 'publ_manuscript_incl'
_definition
 
;
Data items in the PUBL_MANUSCRIPT_INCL category allow
               the authors of a manuscript submitted for publication to list
               data names that should be added to the standard request list
               employed by journal printing software. Although these fields are
               primarily intended to identify CIF data items that the author
               wishes to include in a published paper, they can also be used
               to identify data names created so that non-CIF items can be
               included in the publication. Note that *_item names MUST be
               enclosed in single quotes.
;

_list  no 
_name '_publ_manuscript_incl_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _publ_manuscript_incl_extra_item
    _publ_manuscript_incl_extra_info
    _publ_manuscript_incl_extra_defn
    #
    # Include Hydrogen Bonding Geometry Description
    # =============================================
    # Name                             explanation    standard?
    # ----                             -----------    ---------
      '_geom_hbond_atom_site_label_D'  'H-bond donor'     yes
      '_geom_hbond_atom_site_label_H'  'H-bond hydrogen'  yes
      '_geom_hbond_atom_site_label_A'  'H-bond acceptor'  yes
      '_geom_hbond_distance_DH'        'H-bond D-H'       yes
      '_geom_hbond_distance_HA'        'H-bond H...A'     yes
      '_geom_hbond_distance_DA'        'H-bond D...A'     yes
      '_geom_hbond_angle_DHA'          'H-bond D-H...A'   yes

;
  
;
Example 1 - directive to include hydrogen bonding table, including
                cosmetic headings in comments.
;
 
  
;
loop_
    _publ_manuscript_incl_extra_item
    _publ_manuscript_incl_extra_info
    _publ_manuscript_incl_extra_defn
      '_atom_site_symmetry_multiplicity' 'to emphasise special sites'      yes
      '_chemical_compound_source'        'rare material, unusual source'   yes
      '_reflns_d_resolution_high'        'limited data is a problem here'  yes
      '_crystal_magnetic_permeability'   'unusual value for this material'  no
;
  
;
Example 2 - hypothetical example including both standard CIF data items
                and a non-CIF quantity which the author wishes to list.
;
 

 loop_
   _category_mandatory.name                                                   
  '_publ_manuscript_incl_extra_item'

_space_group_name_H-M_alt
_category 'space_group'
_definition
 
;
_space_group_name_H-M_alt allows for any Hermann-Mauguin symbol
               to be given. The way in which this item is used is determined
               by the user and in general is not intended to be interpreted by
               computer. It may, for example, be used to give one of the
               extended Hermann-Mauguin symbols given in Table 4.3.1 of
               International Tables for Crystallography Vol. A (1995) or
               a Hermann-Mauguin symbol for a conventional or unconventional
               setting.  

               Each component of the space group name is separated by a 
               space or underscore. The use of space is strongly
               recommended.  The underscore is only retained because it
               was used in earlier archived files. It should not be 
               used in new CIFs. Subscripts should appear without special
               symbols. Bars should be given as negative signs before the
               numbers to which they apply. 

               The commonly used Hermann-Mauguin symbol determines the space
               group type uniquely but a given space group type may be
               described by more than one Hermann-Mauguin symbol. The space
               group type is best described using _space_group_IT_number.

               The Hermann-Mauguin symbol may contain information on the
               choice of basis though not on the choice of origin. To
               define the setting uniquely use _space_group_name_Hall or
               list the symmetry operations.
;

_list  both 
_list_reference '_space_group_id'
_name '_space_group_name_H-M_alt'
_related_function  alternate 
_related_item '_symmetry_space_group_name_H-M'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
                                   _space_group_name_H-M_alt
                                    'C m c m' 
                                    'C 2/c 2/m 21/m' 
                                    'A m a m'        
;
  'three examples for the space group number 63'

_citation_journal_id_CSD
_category  citation 
_definition
 
;
The Cambridge Structural Database (CSD) code assigned to the
               journal cited; relevant for journal articles. This is also the
               system used at the Protein Data Bank (PDB).
;

_example  0070 
_list  yes 
_list_reference '_citation_id'
_name '_citation_journal_id_CSD'
_type  char 
_type_conditions  none 

_atom_site_aniso_U_23
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_23'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_diffrn_detector_details
_category 'diffrn_detector'
_definition 'A description of special aspects of the radiation detector.'
_list  no 
_name '_diffrn_detector_details'
_type  char 
_type_conditions  none 

_diffrn_orient_refln_[]
_category 'category_overview'
_category.id 'diffrn_orient_refln'
_definition
 
;
Data items in the DIFFRN_ORIENT_REFLN category record details
               about the reflections that define the orientation matrix used in
               measurement of diffraction intensities.
;

_list  no 
_name '_diffrn_orient_refln_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _diffrn_orient_refln_index_h
    _diffrn_orient_refln_index_k
    _diffrn_orient_refln_index_l
    _diffrn_orient_refln_angle_theta
    _diffrn_orient_refln_angle_phi
    _diffrn_orient_refln_angle_omega
    _diffrn_orient_refln_angle_kappa
      -3   2   3    7.35   44.74   2.62    17.53
      -4   1   0    9.26   83.27   8.06     5.79
       0   0   6    5.85  -43.93 -25.36    86.20
       2   1   3    7.36  -57.87   6.26     5.42
       0   0  -6    5.85 -161.59  36.96   -86.79
      -3   1   0    6.74   80.28   5.87     2.60
       2   0   3    5.86  -76.86  -0.17    21.34
       0   0  12   11.78  -44.02 -19.51    86.41
       0   0 -12   11.78 -161.67  42.81   -86.61
      -5   1   0   11.75   86.24   9.16     7.44
       0   4   6   11.82  -19.82  10.45     4.19
       5   0   6   14.13  -77.28  10.17    15.34
       8   0   0   20.79  -77.08  25.30   -13.96
;
  'Example 1 - typical output listing from Enraf-Nonius CAD-4 diffractometer.'

 loop_
   _category_mandatory.name                                                   
  '_diffrn_orient_refln_index_k'
  '_diffrn_orient_refln_index_h'
  '_diffrn_orient_refln_index_l'

_computing_[]
_category 'category_overview'
_category.id  computing 
_definition
 
;
Data items in the COMPUTING category record details about the
               computer programs used in the crystal structure analysis.
;

_list  no 
_name '_computing_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_computing_data_collection
                                     'CAD-4 (Enraf-Nonius, 1989)'
    _computing_cell_refinement
                                     'CAD-4 (Enraf-Nonius, 1989)'
    _computing_data_reduction        'CFEO (Solans, 1978)'
    _computing_structure_solution
                                     'SHELXS86 (Sheldrick, 1990)'
    _computing_structure_refinement
                                     'SHELXL93 (Sheldrick, 1993)'
    _computing_molecular_graphics    'ORTEPII (Johnson, 1976)'
    _computing_publication_material  'PARST (Nardelli, 1983)'
;
  
;
Example 1 - Rodr\'iguez-Romero, Ruiz-P\'erez & Solans [(1996).
                Acta Cryst. C52, 1415-1417].
;
 

_diffrn_radiation_polarisn_ratio
_category 'diffrn_radiation'
_definition
 
;
Polarisation ratio of the diffraction beam incident on the
               crystal. It is the ratio of the perpendicularly polarised to the
               parallel polarised component of the radiation. The perpendicular
               component forms an angle of _diffrn_radiation_polarisn_norm to
               the normal to the diffraction plane of the sample (i.e. the plane
               containing the incident and reflected beams).
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_radiation_polarisn_ratio'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_exptl_absorpt_correction_T_max
_category  exptl 
_definition
 
;
The maximum and minimum transmission factors for the crystal
                and radiation. These factors are also referred to as the
                absorption correction A or 1/A*.
;

_enumeration_range  0.0:1.0 
_list  no 
_name '_exptl_absorpt_correction_T_max'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_refine_ls_matrix_type
_category  refine 
_definition 'Type of matrix used to accumulate the least-squares derivatives.'
_enumeration_default  full 
_list  no 
_name '_refine_ls_matrix_type'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   full   full 
   fullcycle  'full with fixed elements per cycle'
   atomblock  'block diagonal per atom'
   userblock  'user-defined blocks'
   diagonal  'diagonal elements only'
   sparse  'selected elements only'

_diffrn_radiation_wavelength_id
_category 'diffrn_radiation_wavelength'
_definition
 
;
An arbitrary code identifying each value of
               _diffrn_radiation_wavelength. Items in the DIFFRN_RADIATION
               category are looped when multiple wavelengths are used.
               This code is used to link with the _diffrn_refln_ list. It
               must match with one of the _diffrn_refln_wavelength_id codes.
;

_list  yes 
_list_link_child '_diffrn_refln_wavelength_id'
_list_mandatory  yes 
_name '_diffrn_radiation_wavelength_id'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   x1 
   x2 
   neut 

_audit_link_[]
_category 'category_overview'
_category.id 'audit_link'
_definition
 
;
Data items in the AUDIT_LINK category record details about the
               relationships between data blocks in the current CIF.
;

_list  no 
_name '_audit_link_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _audit_link_block_code
    _audit_link_block_description
       .             'discursive text of paper with two structures'
       morA_(1)      'structure 1 of 2'
       morA_(2)      'structure 2 of 2'
;
  
;
Example 1 - multiple structure paper, as illustrated
                in A Guide to CIF for Authors (1995). IUCr: Chester.
;
 
  
;
loop_
    _audit_link_block_code
    _audit_link_block_description
       .        'publication details'
       KSE_COM  'experimental data common to ref./mod. structures'
       KSE_REF  'reference structure'
       KSE_MOD  'modulated structure'
;
  
;
Example 2 - example file for the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~.
;
 

 loop_
   _category_mandatory.name                                                   
  '_audit_link_block_code'

_reflns_scale_group_code
_category 'reflns_scale'
_definition
 
;
The code identifying a scale _reflns_scale_meas_. These are
               linked to the _refln_ list by the _refln_scale_group_code. These
               codes need not correspond to those in the _diffrn_scale_ list.
;

_list  yes 
_list_link_child '_refln_scale_group_code'
_list_mandatory  yes 
_name '_reflns_scale_group_code'
_type  char 
_type_conditions  none 

_refine_ls_restrained_S_obs
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S' for observed
               reflections, after the final cycle of least squares. This
               parameter explicitly includes the restraints applied in the
               least-squares process.  See also _refine_ls_goodness_of_fit_
               definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_restrained_S_obs'
_related_function  replace 
_related_item '_refine_ls_restrained_S_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_class_R_I_factor
_category 'reflns_class'
_definition
 
;
For each reflection class, the residual factor R(I) for the
               reflections judged significantly intense (i.e. satisfying the
               threshold specified by _reflns_threshold_expression) and
               included in the refinement.

               This is most often calculated in Rietveld refinements
               of powder data, where it is referred to as R~B~ or R~Bragg~

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the reflections of this class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_reflns_class_code'
_name '_reflns_class_R_I_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_refinement_flags_posn
_category 'atom_site'
_definition
 
;
A code which indicates the refinement restraints or constraints
               applied to the positional coordinates of this site.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_refinement_flags_posn'
_related_function  alternate 
_related_item '_atom_site_refinement_flags_posn'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   .  'no constraints on  positional coordinates'
   D  'distance or angle restraint on positional coordinates'
   G  'rigid group refinement of positional coordinates'
   R  'riding-atom site attached to non-riding atom'
   S  'special position constraint on positional coordinates'
   DG  'combination of the above constraints'
   DR  'combination of the above constraints'
   DS  'combination of the above constraints'
   GR  'combination of the above constraints'
   GS  'combination of the above constraints'
   RS  'combination of the above constraints'
   DGR  'combination of the above constraints'
   DGS  'combination of the above constraints'
   DRS  'combination of the above constraints'
   GRS  'combination of the above constraints'
   DGRS  'combination of the above constraints'

_geom_bond_site_symmetry_2
_category 'geom_bond'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the bond. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_bond_atom_site_label_'
_name '_geom_bond_site_symmetry_2'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_exptl_crystal_colour
_category 'exptl_crystal'
_definition 'The colour of the crystal.'
_example 'dark green'
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_colour'
_type  char 
_type_conditions  none 

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_exptl_crystal_colour_lustre'
   alternate  '_exptl_crystal_colour_modifier'
   alternate  '_exptl_crystal_colour_primary'

_symmetry_equiv_pos_site_id
_category 'symmetry_equiv'
_definition
 
;
A code identifying each entry in the _symmetry_equiv_pos_as_xyz
               list. It is normally the sequence number of the entry in that
               list, and should be identified with the code 'n' in
               _geom_*_symmetry_ codes of the form 'n_klm'.
;

_list  yes 
_list_reference '_symmetry_equiv_pos_as_xyz'
_name '_symmetry_equiv_pos_site_id'
_related_function  replace 
_related_item '_space_group_symop_id'
_type  numb 
_type_conditions  none 

_chemical_formula_sum
_category 'chemical_formula'
_definition
 
;
See _chemical_formula_[] for the rules for writing chemical
               formulae in which all discrete bonded residues and ions are
               summed over the constituent elements, following the ordering
               given in general rule 5 in _chemical_formula_[]. Parentheses
               are not normally used.
;

_list  no 
_name '_chemical_formula_sum'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'C18 H19 N7 O8 S'

_publ_contact_letter
_category  publ 
_definition 'A letter submitted to the journal editor by the contact author.'
_list  no 
_name '_publ_contact_letter'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_12
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_12'
_type  numb 
_type_conditions  none 

_chemical_conn_atom_type_symbol
_category 'chemical_conn_atom'
_definition
 
;
A code identifying the atom type. This code must match an
               _atom_type_symbol code in the _atom_type_ list; or be a
               recognisable element symbol.
;

_list  yes 
_list_mandatory  yes 
_name '_chemical_conn_atom_type_symbol'
_type  char 
_type_conditions  none 

_atom_type_scat_dispersion_real
_category 'atom_type'
_definition
 
;
The imaginary and real components of the anomalous dispersion
               scattering factors, f'' and f', in electrons, for this atom type
               and the radiation given in _diffrn_radiation_wavelength.
;

_enumeration_default  0.0 
_list  yes 
_list_reference '_atom_type_symbol'
_name '_atom_type_scat_dispersion_real'
_type  numb 
_type_conditions  none 

_diffrn_orient_refln_angle_phi
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_phi'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_geom_torsion_publ_flag
_category 'geom_torsion'
_definition
 
;
This code signals if the torsion angle is referred to in a
               publication or should be placed in a table of significant
               torsion angles.
;

_enumeration_default  no 
_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion_publ_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'do not include angle in special list'
   n  'abbreviation for "no"'
   yes  'do include angle in special list'
   y  'abbreviation for "yes"'

_cell_measurement_theta_max
_category  cell 
_definition
 
;
The maximum and minimum theta angles in degrees of reflections
               used to measure the unit cell.
;

_enumeration_range  0.0:90.0 
_list  no 
_name '_cell_measurement_theta_max'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_refine_ls_restrained_S_gt
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S' for
               significantly intense reflections (satisfying
               _reflns_threshold_expression) after the final cycle
               of least squares. This parameter explicitly includes
               the restraints applied in the least-squares process.
               See also _refine_ls_goodness_of_fit_ definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_restrained_S_gt'
_related_function  alternate 
_related_item '_refine_ls_restrained_S_obs'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_orient_matrix_UB_22
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_22'
_type  numb 
_type_conditions  none 

_diffrn_orient_matrix_UB_23
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_23'
_type  numb 
_type_conditions  none 

_citation_[]
_category 'category_overview'
_category.id  citation 
_definition
 
;
Data items in the CITATION category record details about the
               literature cited relevant to the contents of the data block.
;

_list  no 
_name '_citation_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _citation_id
    _citation_coordinate_linkage
    _citation_title
    _citation_country
    _citation_page_first
    _citation_page_last
    _citation_year
    _citation_journal_abbrev
    _citation_journal_volume
    _citation_journal_issue
    _citation_journal_id_ASTM
    _citation_journal_id_ISSN
    _citation_book_title
    _citation_book_publisher
    _citation_book_id_ISBN
    _citation_special_details
      primary  yes
    ; Crystallographic analysis of a complex between human
      immunodeficiency virus type 1 protease and
      acetyl-pepstatin at 2.0-Angstroms resolution.
    ;
      US  14209  14219  1990  'J. Biol. Chem.'  265  .
      HBCHA3  0021-9258  .  .  .
    ; The publication that directly relates to this coordinate
      set.
    ;
      2  no
    ; Three-dimensional structure of aspartyl-protease from
      human immunodeficiency virus HIV-1.
    ;
      UK  615  619  1989  'Nature'  337  .
      NATUAS  0028-0836  .  .  .
    ; Determination of the structure of the unliganded enzyme.
    ;
      3 no
    ; Crystallization of the aspartylprotease from human
      immunodeficiency virus, HIV-1.
    ;
      US  1919  1921  1989  'J. Biol. Chem.'  264  .
      HBCHA3  0021-9258  .  .  .
    ; Crystallization of the unliganded enzyme.
    ;
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

 loop_
   _category_mandatory.name                                                   
  '_citation_id'

_chemical_conn_atom_display_x
_category 'chemical_conn_atom'
_definition
 
;
The 2D Cartesian coordinates (x,y) of the position of this atom
               in a recognisable chemical diagram. The coordinate origin is at
               the lower left corner, the x axis is horizontal and the y axis is
               vertical. The coordinates must lie in the range 0.0 to 1.0. These
               coordinates can be obtained from projections of a suitable
               uncluttered view of the molecular structure. If absent, values
               will be assigned by the journal or database staff.
;

_enumeration_range  0.0:1.0 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_display_x'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_diffrn_measurement_[]
_category 'category_overview'
_category.id 'diffrn_measurement'
_definition
 
;
Data items in the DIFFRN_MEASUREMENT category refer to the
               mounting of the sample and to the goniometer on which it is
               mounted.
;

_list  no 
_name '_diffrn_measurement_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_measurement_device_type
                                       'Philips PW1100/20 diffractometer'
    _diffrn_measurement_method          \q/2\q
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_refln_B_meas
_category  refln 
_definition
 
;
The calculated and measured structure-factor component B
               (in electrons for X-ray diffraction).

               B =|F|sin(phase)
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_B_meas'
_type  numb 
_type_conditions  none 

_diffrn_ambient_pressure_lt
_category  diffrn 
_definition
 
;
The mean hydrostatic pressure in kilopascals above which (*_gt)
               or below which (*_lt) the intensities were measured. These
               items allow for a pressure range to be given.

               _diffrn_ambient_pressure should always be used in
               preference to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_pressure_lt'
_related_function  alternate 
_related_item '_diffrn_ambient_pressure'
_type  numb 
_type_conditions  none 
_units  kPa 
_units_detail  kilopascals 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_CSD_history
_category  database 
_definition
 
;
A history of changes made by the Cambridge Crystallographic Data
               Centre and incorporated into the Cambridge Structural Database
               (CSD).
;

_list  no 
_name '_database_CSD_history'
_type  char 
_type_conditions  none 

_exptl_crystal_thermal_history
_category 'exptl_crystal'
_definition
 
;
Relevant details concerning the thermal history of the
               sample.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_thermal_history'
_type  char 
_type_conditions  none 

_cell_measurement_reflns_used
_category  cell 
_definition
 
;
The total number of reflections used to determine the unit cell.
               These reflections may be specified as _cell_measurement_refln_
               data items.
;

_list  no 
_name '_cell_measurement_reflns_used'
_type  numb 
_type_conditions  none 

_refine_ls_goodness_of_fit_ref
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S for all
               reflections included in the refinement, after the final cycle
               of refinement. Ideally, account should be taken of parameters
               restrained in the least squares. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum | w | Y(obs) - Y(calc) |^2^ |  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_goodness_of_fit_ref'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_contact_author_address
_category 'audit_contact_author'
_definition
 
;
The mailing address of the author of the data block to whom
               correspondence should be addressed.
;

_example
 
;
Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;

_list  no 
_name '_audit_contact_author_address'
_type  char 
_type_conditions  none 

_atom_sites_fract_tran_matrix_33
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_33'
_type  numb 
_type_conditions  none 

_refln_crystal_id
_category  refln 
_definition
 
;
Code identifying each crystal if multiple crystals are used. Is
               used to link with _exptl_crystal_id in the _exptl_crystal_ list.
;

_list  yes 
_list_link_parent '_exptl_crystal_id'
_list_reference '_refln_index_'
_name '_refln_crystal_id'
_type  char 
_type_conditions  none 

_refine_ls_shift/su_max
_category  refine 
_definition
 
;
The largest ratio of the final least-squares parameter
               shift divided by the final standard uncertainty.
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_shift/su_max'
_related_function  alternate 
_related_item '_refine_ls_shift/esd_max'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_counts_bg_2
_category 'diffrn_refln'
_definition
 
;
The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_counts_bg_2'
_type  numb 
_type_conditions  none 

_audit_contact_author_email
_category 'audit_contact_author'
_definition
 
;
The electronic mail address of the author of the data block
               to whom correspondence should be addressed, in a form
               recognisable to international networks.
;

_list  no 
_name '_audit_contact_author_email'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   name@host.domain.country 
   bm@iucr.org 

_exptl_crystal_colour_lustre
_category 'exptl_crystal'
_definition
 
;
The enumeration list of standardized names developed for the
              International Center for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green', 
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_colour_lustre'
_related_function  alternate 
_related_item '_exptl_crystal_colour'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   metallic 
   dull 
   clear 

_diffrn_detector_[]
_category 'category_overview'
_category.id 'diffrn_detector'
_definition
 
;
Data items in the DIFFRN_DETECTOR category describe the
               detector used to measure the scattered radiation, including
               any analyser and post-sample collimation.
;

_list  no 
_name '_diffrn_detector_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_detector                    'multiwire'
    _diffrn_detector_type               'Siemens'
;
  
;
Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
 

_atom_site_type_symbol
_category 'atom_site'
_definition
 
;
A code to identify the atom specie(s) occupying this site.
               This code must match a corresponding _atom_type_symbol. The
               specification of this code is optional if component 0 of the
               _atom_site_label is used for this purpose. See _atom_type_symbol.
;

_list  yes 
_list_link_child '_atom_site_aniso_type_symbol'
_list_link_parent '_atom_type_symbol'
_list_reference '_atom_site_label'
_name '_atom_site_type_symbol'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   Cu 
   Cu2+ 
   dummy 
   Fe3+Ni2+ 
   S- 
   H* 
   H(SDS) 

_diffrn_orient_refln_angle_kappa
_category 'diffrn_orient_refln'
_definition
 
;
Diffractometer angles in degrees of a reflection used to define
               the orientation matrix. See _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

_list  yes 
_list_reference '_diffrn_orient_refln_index_'
_name '_diffrn_orient_refln_angle_kappa'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_atom_type_[]
_category 'category_overview'
_category.id 'atom_type'
_definition
 
;
Data items in the ATOM_TYPE category record details about
               properties of the atoms that occupy the atom sites, such as the
               atomic scattering factors.
;

_list  no 
_name '_atom_type_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _atom_type_symbol
    _atom_type_oxidation_number
    _atom_type_number_in_cell
    _atom_type_scat_dispersion_real
    _atom_type_scat_dispersion_imag
    _atom_type_scat_source
      C  0  72  .017  .009  International_Tables_Vol_IV_Table_2.2B
      H  0  100  0     0    International_Tables_Vol_IV_Table_2.2B
      O  0  12  .047  .032  International_Tables_Vol_IV_Table_2.2B
      N  0  4   .029  .018  International_Tables_Vol_IV_Table_2.2B
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_atom_type_symbol'

_diffrn_reflns_[]
_category 'category_overview'
_category.id 'diffrn_reflns'
_definition
 
;
Data items in the DIFFRN_REFLNS category record details about
               the set of intensities measured in the diffraction experiment.

               The DIFFRN_REFLNS data items specify the parameters that apply
               to all intensity measurements. The DIFFRN_REFLNS data items
               are not looped.

               (The DIFFRN_REFLN data items refer to individual intensity
               measurements, and must be included in looped lists.)
;

_list  no 
_name '_diffrn_reflns_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_reflns_number              1592
    _diffrn_reflns_av_R_equivalents    0
    _diffrn_reflns_av_unetI/netI       .027
    _diffrn_reflns_limit_h_min         0
    _diffrn_reflns_limit_h_max         6
    _diffrn_reflns_limit_k_min        -17
    _diffrn_reflns_limit_k_max         0
    _diffrn_reflns_limit_l_min         0
    _diffrn_reflns_limit_l_max         22
    _diffrn_reflns_theta_min           3.71
    _diffrn_reflns_theta_max           61.97
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_database_code_depnum_ccdc_archive
_category  database 
_definition
 
;
Deposition numbers assigned by the Cambridge Crystallographic
               Data Centre (CCDC) to files containing structural information
               archived by the CCDC.
;

_list  no 
_name '_database_code_depnum_ccdc_archive'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_transform_axes
_category 'atom_sites'
_definition
 
;
A description of the relative alignment of the crystal cell
               axes to the  Cartesian orthogonal axes as applied in the
               transformation matrix _atom_sites_Cartn_tran_matrix_.
;

_example 'a parallel to x; b in the plane of y & z'
_list  no 
_name '_atom_sites_Cartn_transform_axes'
_type  char 
_type_conditions  none 

_publ_section_acknowledgements
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_acknowledgements'
_type  char 
_type_conditions  none 

_diffrn_detector
_category 'diffrn_detector'
_definition 'The general class of the radiation detector.'
_list  no 
_name '_diffrn_detector'
_related_function  alternate 
_related_item '_diffrn_radiation_detector'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'photographic film'
  'scintillation counter'
  'CCD plate'
  'BF~3~ counter'

_refine_ls_class_code
_category 'refine_ls_class'
_definition
 
;
The code identifying a certain reflection class. This code must
               match a _reflns_class_code.
;

_list  yes 
_list_link_parent '_reflns_class_code'
_name '_refine_ls_class_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   m1 
   s2 

_diffrn_measurement_details
_category 'diffrn_measurement'
_definition 'A description of special aspects of the intensity measurement.'
_example '440 frames of 0.25\%'
_list  no 
_name '_diffrn_measurement_details'
_type  char 
_type_conditions  none 

_diffrn_refln_angle_omega
_category 'diffrn_refln'
_definition
 
;
The diffractometer angles in degrees of a reflection. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_angle_omega'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

_audit_author_address
_category 'audit_author'
_definition
 
;
The address of an author of this data block. If there are
               multiple authors, _audit_author_address is looped with
               _audit_author_name.
;

_example
 
;
Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;

_list  yes 
_list_reference '_audit_author_name'
_name '_audit_author_address'
_type  char 
_type_conditions  none 

_refine_ls_goodness_of_fit_all
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S for all
               reflections after the final cycle of refinement.
               Ideally, account should be taken of parameters restrained
               in the least squares. See also _refine_ls_restrained_S_
               definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_goodness_of_fit_all'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_refine_ls_R_factor_all
_category  refine 
_definition
 
;
Residual factor for all reflections satisfying the
               resolution limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_R_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_ambient_temperature_gt
_category  diffrn 
_definition
 
;
The mean temperature in kelvins above which (*_gt) or below
              which (*_lt) the intensities were measured.  These items allow
              a range of temperatures to be given. 

              _diffrn_ambient_temperature should always be used in preference
              to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_temperature_gt'
_related_function  alternate 
_related_item '_diffrn_ambient_temperature'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_geom_bond_[]
_category 'category_overview'
_category.id 'geom_bond'
_definition
 
;
Data items in the GEOM_BOND category record details about
               bonds, as calculated from the contents of the ATOM, CELL,
               and SYMMETRY data.
;

_list  no 
_name '_geom_bond_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _geom_bond_atom_site_label_1
    _geom_bond_atom_site_label_2
    _geom_bond_distance
    _geom_bond_site_symmetry_1
    _geom_bond_site_symmetry_2
    _geom_bond_publ_flag
      O1  C2   1.342(4)  1_555  1_555  yes
      O1  C5   1.439(3)  1_555  1_555  yes
      C2  C3   1.512(4)  1_555  1_555  yes
      C2  O21  1.199(4)  1_555  1_555  yes
      C3  N4   1.465(3)  1_555  1_555  yes
      C3  C31  1.537(4)  1_555  1_555  yes
      C3  H3   1.00(3)   1_555  1_555  no
      N4  C5   1.472(3)  1_555  1_555  yes
    # - - - - data truncated for brevity - - - -
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

 loop_
   _category_mandatory.name                                                   
  '_geom_bond_atom_site_label_1'
  '_geom_bond_atom_site_label_2'

_publ_contact_author_fax
_category  publ 
_definition
 
;
Facsimile telephone number of the author submitting the
               manuscript and data block.

               The recommended style includes the international dialing
               prefix, the area code in parentheses, followed by the
               local number with no spaces. The earlier convention of including
               the international dialing prefixes in parentheses is no longer
               recommended.
;

_list  no 
_name '_publ_contact_author_fax'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   12(34)9477334 
   12()349477334 

_geom_contact_atom_site_label_1
_category 'geom_contact'
_definition
 
;
The labels of two atom sites that are within contact distance.
               The labels must match _atom_site_label codes in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_contact_atom_site_label_1'
_type  char 
_type_conditions  none 

_publ_section_exptl_refinement
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_exptl_refinement'
_type  char 
_type_conditions  none 

_geom_contact_atom_site_label_2
_category 'geom_contact'
_definition
 
;
The labels of two atom sites that are within contact distance.
               The labels must match _atom_site_label codes in the atom list.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_geom_contact_atom_site_label_2'
_type  char 
_type_conditions  none 

_chemical_temperature_sublimation_gt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above which
              (*_gt) the solid is known to sublime. These items allow a
              range of temperatures to be given. 

              _chemical_temperature_sublimation should always be used in
              preference to these items whenever possible.
;

_enumeration_range  0.0: 
_example  350 
_list  no 
_name '_chemical_temperature_sublimation_gt'
_related_function  alternate 
_related_item '_chemical_temperature_sublimation'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_reflns_number_total
_category  reflns 
_definition
 
;
The total number of reflections in the _refln_ list (not the
                _diffrn_refln_ list). It may include Friedel equivalent
               reflections (i.e. those which are symmetry equivalent under the
               Laue symmetry but inequivalent under the crystal class)
               according to the nature of the structure and the procedures
               used. The special characteristics of the reflections included
               in the _refln_ list should be given in the item
               _reflns_special_details.
;

_enumeration_range  0: 
_list  no 
_name '_reflns_number_total'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_database_journal_CSD
_category  database 
_definition
 
;
The ASTM CODEN designator for a journal as given in the
               Chemical Source List maintained by the Chemical Abstracts
               Service, and the journal code used in the Cambridge Structural
               Database.
;

_list  no 
_name '_database_journal_CSD'
_type  char 
_type_conditions  none 

_reflns_shell_number_possible
_category 'reflns_shell'
_definition
 
;
The number of unique reflections it is possible to measure in
               this reflection shell.
;

_enumeration_range  0: 
_list  yes 
_name '_reflns_shell_number_possible'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_theta_max
_category 'diffrn_reflns'
_definition 'Maximum theta angle in degrees for the measured intensities.'
_enumeration_range  0.0:90.0 
_list  no 
_name '_diffrn_reflns_theta_max'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_refine_ls_goodness_of_fit_gt
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S for
               significantly intense reflections, (see
               _reflns_threshold_expression), after the final cycle of
               refinement. Ideally, account should be taken of parameters
               restrained in the least squares. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_goodness_of_fit_gt'
_related_function  alternate 
_related_item '_refine_ls_goodness_of_fit_obs'
_type  numb 
_type_conditions  esd 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_properties_biological
_category  chemical 
_definition
 
;
A free description of the biological properties of the
               material.
;

_list  no 
_name '_chemical_properties_biological'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  
;
diverse biological activities including use as a 
               laxative and strong antibacterial activity against
               S. aureus and weak activity against 
               cyclooxygenase-1 (COX-1)
;
 
  
;
antibiotic activity against Bacillus subtilis 
               (ATCC 6051) but no significant activity against
               Candida albicans (ATCC 14053), Aspergillus flavus 
               (NRRL 6541) and Fusarium verticillioides (NRRL
               25457)
;
 
  'weakly potent lipoxygenase nonredox inhibitor'
  
;
no influenza A virus sialidase inhibitory and
               plaque reduction activities
;
 
  'low toxicity against Drosophila melanogaster'

_chemical_conn_atom_display_y
_category 'chemical_conn_atom'
_definition
 
;
The 2D Cartesian coordinates (x,y) of the position of this atom
               in a recognisable chemical diagram. The coordinate origin is at
               the lower left corner, the x axis is horizontal and the y axis is
               vertical. The coordinates must lie in the range 0.0 to 1.0. These
               coordinates can be obtained from projections of a suitable
               uncluttered view of the molecular structure. If absent, values
               will be assigned by the journal or database staff.
;

_enumeration_range  0.0:1.0 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_display_y'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   1.0   1.0 
   1.0   0.0 
   0.0   0.0 

_reflns_shell_meanI_over_uI_gt
_category 'reflns_shell'
_definition
 
;
The ratio of the mean of the intensities of the significantly
               intense reflections (see _reflns_threshold_expression) in
               this shell to the mean of the standard uncertainties of the
               intensities of the significantly intense reflections in the
               resolution shell.
;

_list  yes 
_name '_reflns_shell_meanI_over_uI_gt'
_type  numb 
_type_conditions  none 

 loop_
   _related_function                                                          
   _related_item                                                              
   alternate  '_reflns_shell_meanI_over_sigI_gt'
   alternate  '_reflns_shell_meanI_over_sigI_obs'

_diffrn_reflns_av_sigmaI/netI
_category 'diffrn_reflns'
_definition 'Measure [sum u(net I)|/sum|net I|] for all measured reflections.'
_enumeration_range  0.0: 
_list  no 
_name '_diffrn_reflns_av_sigmaI/netI'
_related_function  replace 
_related_item '_diffrn_reflns_av_unetI/netI'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_cell_measurement_refln_[]
_category 'category_overview'
_category.id 'cell_measurement_refln'
_definition
 
;
Data items in the CELL_MEASUREMENT_REFLN category record
               details about the reflections used in determination of the
               crystallographic cell parameters.

               The _cell_measurement_refln_ data items would in general be used
               only for diffractometer measurements.
;

_list  no 
_name '_cell_measurement_refln_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
     _cell_measurement_refln_index_h
     _cell_measurement_refln_index_k
     _cell_measurement_refln_index_l
     _cell_measurement_refln_theta
       -2    4    1          8.67
        0    3    2          9.45
        3    0    2          9.46
       -3    4    1          8.93
       -2    1   -2          7.53
       10    0    0         23.77
        0   10    0         23.78
       -5    4    1         11.14
      # - - - - data truncated for brevity - - - -
;
  
;
Example 1 - extracted from the CAD-4 listing of Rb~2~S~2~O~6~ at room
                temperature (not yet published).
;
 

 loop_
   _category_mandatory.name                                                   
  '_cell_measurement_refln_index_k'
  '_cell_measurement_refln_index_l'
  '_cell_measurement_refln_index_h'

_geom_angle_publ_flag
_category 'geom_angle'
_definition
 
;
This code signals if the angle is referred to in a publication or
               should be placed in a table of significant angles.
;

_enumeration_default  no 
_list  yes 
_list_reference '_geom_angle_atom_site_label_'
_name '_geom_angle_publ_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   no  'do not include angle in special list'
   n  'abbreviation for "no"'
   yes  'do include angle in special list'
   y  'abbreviation for "yes"'

_chemical_optical_rotation
_category  chemical 
_definition
 
;
The optical rotation in solution of the compound is
               specified in the following format:
                    '[\a]^TEMP^~WAVE~ = SORT (c = CONC, SOLV)'
               where:
                 TEMP is the temperature of the measurement in degrees
                      Celsius,
                 WAVE is an indication of the wavelength of the light
                      used for the measurement,
                 CONC is the concentration of the solution given as the
                      mass of the substance in g in 100 ml of solution,
                 SORT is the signed value (preceded by a + or a - sign)
                      of 100.\a/(l.c), where \a is the signed optical
                      rotation in degrees measured in a cell of length l in
                      dm and c is the value of CONC in g, and
                 SOLV is the chemical formula of the solvent.
;

_example '[\a]^25^~D~ = +108 (c = 3.42, CHCl~3~)'
_list  no 
_name '_chemical_optical_rotation'
_type  char 
_type_conditions  none 

_atom_sites_Cartn_tran_matrix_22
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_22'
_type  numb 
_type_conditions  none 

_diffrn_refln_detect_slit_horiz
_category 'diffrn_refln'
_definition
 
;
Total slit apertures in degrees in the diffraction plane
               (*_horiz) and perpendicular to the diffraction plane (*_vert).
;

_enumeration_range  0.0:90.0 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_detect_slit_horiz'
_type  numb 
_type_conditions  none 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_diffrn_orient_matrix_type
_category 'diffrn_orient_matrix'
_definition
 
;
A description of the orientation matrix type and how it should
               be applied to define the orientation of the crystal precisely
               with respect to the diffractometer axes.
;

_list  no 
_name '_diffrn_orient_matrix_type'
_type  char 
_type_conditions  none 

_diffrn_scale_group_code
_category 'diffrn_scale_group'
_definition
 
;
The code identifying a specific measurement group (e.g. for
               multi-film or multi-crystal data). The code must match a
               _diffrn_refln_scale_group_code in the reflection list.
;

_list  yes 
_list_link_child '_diffrn_refln_scale_group_code'
_list_mandatory  yes 
_name '_diffrn_scale_group_code'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   1 
   2 
   3 
   s1 
   A 
   B 
   c1 
   c2 
   c3 

_refln_F_squared_sigma
_category  refln 
_definition
 
;
Calculated, measured and estimated standard uncertainty (derived
               from measurement) of the squared structure factors (in electrons
               squared for X-ray diffraction).
;

_list  yes 
_list_reference '_refln_index_'
_name '_refln_F_squared_sigma'
_type  numb 
_type_conditions  none 

_refln_class_code
_category  refln 
_definition
 
;
The code identifying the class to which this reflection has been
               assigned. This code must match a value of _reflns_class_code.
               Reflections may be grouped into classes for a variety of
               purposes. For example, for modulated structures each reflection
               class may be defined by the number m=sum|m~i~|, where the m~i~
               are the integer coefficients that, in addition to h,k,l, index
               the corresponding diffraction vector in the basis defined
               for the reciprocal lattice.
;

_list  yes 
_list_link_parent '_reflns_class_code'
_list_reference '_refln_index_'
_name '_refln_class_code'
_type  char 
_type_conditions  none 

_diffrn_reflns_av_unetI/netI
_category 'diffrn_reflns'
_definition 'Measure [sum u(net I)|/sum|net I|] for all measured reflections.'
_enumeration_range  0.0: 
_list  no 
_name '_diffrn_reflns_av_unetI/netI'
_related_function  alternate 
_related_item '_diffrn_reflns_av_sigmaI/netI'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_calc_flag
_category 'atom_site'
_definition
 
;
A standard code to signal if the site coordinates have been
               determined from the intensities or calculated from the geometry
               of surrounding sites, or have been assigned dummy coordinates.
               The abbreviation 'c' may be used in place of 'calc'.
;

_enumeration_default  d 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_calc_flag'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   d  'determined from diffraction measurements'
   calc  'calculated from molecular geometry'
   c  'abbreviation for "calc"'
   dum  'dummy site with meaningless coordinates'

_diffrn_ambient_pressure_gt
_category  diffrn 
_definition
 
;
The mean hydrostatic pressure in kilopascals above which (*_gt)
               or below which (*_lt) the intensities were measured. These
               items allow for a pressure range to be given.

               _diffrn_ambient_pressure should always be used in
               preference to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_ambient_pressure_gt'
_related_function  alternate 
_related_item '_diffrn_ambient_pressure'
_type  numb 
_type_conditions  none 
_units  kPa 
_units_detail  kilopascals 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_measurement_device
_category 'diffrn_measurement'
_definition
 
;
The general class of goniometer or device used to support
               and orient the specimen.
;

_list  no 
_name '_diffrn_measurement_device'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'three-circle diffractometer'
  'four-circle diffractometer'
  '\k-geometry diffractometer'
  'oscillation camera'
  'precession camera'

_atom_sites_fract_tran_matrix_11
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_11'
_type  numb 
_type_conditions  none 

_refine_diff_density_max
_category  refine 
_definition
 
;
The largest, smallest and root-mean-square-deviation, in
               electrons per angstrom cubed, of the final difference electron
               density. The *_rms value is measured with
               respect to the arithmetic mean density, and is derived from
               summations over each grid point in the asymmetric unit of
               the cell. This quantity is useful for assessing the
               significance of *_min and *_max values, and also for
               defining suitable contour levels.
;

_list  no 
_name '_refine_diff_density_max'
_type  numb 
_type_conditions  esd 
_units 'e_A^-3^'
_units_detail 'electrons per cubic angstrom'

_refine_ls_class_wR_factor_all
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the weighted residual factors for all
               reflections included in the refinement. The reflections also
               satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the reflections of this class. See
               also _refine_ls_class_R_factor_ definitions.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_wR_factor_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_manuscript_processed
_category  publ 
_definition
 
;
The full manuscript of a paper (excluding possibly the figures
               and the tables) output in ASCII characters from a word processor.
               Information about the generation of this data item must be
               specified in the data item _publ_manuscript_creation.
;

_list  no 
_name '_publ_manuscript_processed'
_type  char 
_type_conditions  none 

_diffrn_refln_scan_mode
_category 'diffrn_refln'
_definition
 
;
The code identifying the mode of scanning with a diffractometer.
               See _diffrn_refln_scan_width and _diffrn_refln_scan_mode_backgd.
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_scan_mode'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   om  'omega scan'
   ot  'omega/2theta scan'
   q  'Q-scans (arbitrary reciprocal directions)'

_cell_measurement_refln_index_l
_category 'cell_measurement_refln'
_definition
 
;
Miller indices of a reflection used for measurement of
               the unit cell.
;

_list  yes 
_list_mandatory  yes 
_name '_cell_measurement_refln_index_l'
_type  numb 
_type_conditions  none 

_cell_measurement_refln_index_h
_category 'cell_measurement_refln'
_definition
 
;
Miller indices of a reflection used for measurement of
               the unit cell.
;

_list  yes 
_list_mandatory  yes 
_name '_cell_measurement_refln_index_h'
_type  numb 
_type_conditions  none 

_diffrn_reflns_limit_k_max
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_k_max'
_type  numb 
_type_conditions  none 

_geom_hbond_distance_DH
_category 'geom_hbond'
_definition
 
;
Distances in angstroms between the donor and hydrogen (*_DH),
               hydrogen and acceptor (*_HA) and donor and acceptor (*_DA)
               sites in a hydrogen bond.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_geom_hbond_atom_site_label_'
_name '_geom_hbond_distance_DH'
_type  numb 
_type_conditions  esd 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_sites_fract_tran_matrix_21
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_21'
_type  numb 
_type_conditions  none 

_atom_sites_fract_tran_matrix_23
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITES category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

_list  no 
_name '_atom_sites_fract_tran_matrix_23'
_type  numb 
_type_conditions  none 

_journal_volume
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_volume'
_type  char 
_type_conditions  none 

_symmetry_equiv_[]
_category 'category_overview'
_category.id 'symmetry_equiv'
_definition
 
;
Data items in the SYMMETRY_EQUIV category list the
               symmetry equivalent positions for the space group.
;

_list  no 
_name '_symmetry_equiv_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _symmetry_equiv_pos_as_xyz
        +x,+y,+z  1/2-x,-y,1/2+z  1/2+x,1/2-y,-z  -x,1/2+y,1/2-z
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 
  
;
loop_
    _symmetry_equiv_pos_site_id
    _symmetry_equiv_pos_as_xyz
        1     x,y,z
        2     1/2-x,-y,1/2+z
        3     1/2+x,1/2-y,-z
        4     -x,1/2+y,1/2-z

;
  
;
Example 2 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277]. Formally the value of
                _symmetry_equiv_pos_site_id can be any unique character string;
                it is recommended that it be assigned the sequence number of
                the list of equivalent positions for compatibility with
                older files in which it did not appear.
;
 

_refine_ls_weighting_scheme
_category  refine 
_definition
 
;
The weighting scheme applied in the least-squares process. The
               standard code may be followed by a description of the weight
               (but see _refine_ls_weighting_details for a preferred approach).
;

_enumeration_default  sigma 
_list  no 
_name '_refine_ls_weighting_scheme'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   sigma  "based on measured s.u.'s"
   unit  'unit or no weights applied'
   calc  'calculated weights applied'

_diffrn_radiation_xray_symbol
_category 'diffrn_radiation'
_definition
 
;
The IUPAC symbol for the X-ray wavelength for probe
               radiation.
;

_list  no 
_name '_diffrn_radiation_xray_symbol'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   K-L~3~  'K\a~1~ in older Siegbahn notation'
   K-L~2~  'K\a~2~ in older Siegbahn notation'
   K-M~3~  'K\b~1~ in older Siegbahn notation'
   K-L~2,3~  'use where K-L~3~ and K-L~2~ are not resolved'

_diffrn_reflns_number
_category 'diffrn_reflns'
_definition
 
;
The total number of measured intensities, excluding
               reflections that are classed as systematically absent arising
               from translational symmetry in the crystal unit cell.
;

_enumeration_range  0: 
_list  no 
_name '_diffrn_reflns_number'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_reflns_limit_h_min
_category 'diffrn_reflns'
_definition
 
;
The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

_list  no 
_name '_diffrn_reflns_limit_h_min'
_type  numb 
_type_conditions  none 

_diffrn_radiation_wavelength
_category 'diffrn_radiation_wavelength'
_definition 'The radiation wavelength in angstroms.'
_enumeration_range  0.0: 
_list  both 
_list_reference '_diffrn_radiation_wavelength_id'
_name '_diffrn_radiation_wavelength'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_section_title
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_title'
_type  char 
_type_conditions  none 

_atom_site_adp_type
_category 'atom_site'
_definition
 
;
A standard code used to describe the type of atomic displacement
               parameters used for the site.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_adp_type'
_related_function  alternate 
_related_item '_atom_site_thermal_displace_type'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   Uani  'anisotropic Uij'
   Uiso  'isotropic U'
   Uovl  'overall U'
   Umpe  'multipole expansion U'
   Bani  'anisotropic Bij'
   Biso  'isotropic B'
   Bovl  'overall B'

_refine_ls_class_R_Fsqd_factor
_category 'refine_ls_class'
_definition
 
;
For each reflection class, the residual factor R(F^2^) calculated
               on the squared amplitudes of the observed and calculated
               structure factors, for the reflections judged significantly
               intense (i.e. satisfying the threshold specified by
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the reflections of this class.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refine_ls_class_code'
_name '_refine_ls_class_R_Fsqd_factor'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_refln_intensity_sigma
_category 'diffrn_refln'
_definition
 
;
Standard uncertainty (e.s.d.) of the net intensity calculated
               from the diffraction counts after the attenuator and standard
               scales have been applied.
;

_enumeration_range  0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_intensity_sigma'
_related_function  replace 
_related_item '_diffrn_refln_intensity_u'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_publ_section_experimental
_category  publ 
_definition
 
;
The sections of a manuscript if submitted in parts. As
               an alternative see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

_list  no 
_name '_publ_section_experimental'
_type  char 
_type_conditions  none 

_cell_angle_beta
_category  cell 
_definition
 
;
Unit-cell angles in degrees of the reported structure.
               The values of _refln_index_h, *_k, *_l must correspond to the
               cell defined by these values and _cell_length_a, *_b and *_c.
               The values of _diffrn_refln_index_h, *_k, *_l may not correspond
               to these values if a cell transformation took place following
               the measurement of diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

_enumeration_default  90.0 
_enumeration_range  0.0:180.0 
_list  no 
_name '_cell_angle_beta'
_type  numb 
_type_conditions  esd 
_units  deg 
_units_detail  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   180.0   180.0 
   180.0   0.0 
   0.0   0.0 

_diffrn_refln_counts_net
_category 'diffrn_refln'
_definition
 
;
The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_counts_net'
_type  numb 
_type_conditions  none 

_journal_techeditor_name
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_techeditor_name'
_type  char 
_type_conditions  none 

_geom_special_details
_category  geom 
_definition
 
;
The description of geometrical information not covered by the
               existing data names in the geometry categories, such as
               least-squares planes.
;

_list  no 
_name '_geom_special_details'
_type  char 
_type_conditions  none 

_cell_measurement_radiation
_category  cell 
_definition
 
;
Description of the radiation used to measure the unit-cell data.
               See also  _cell_measurement_wavelength.
;

_list  no 
_name '_cell_measurement_radiation'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   neutron 
  'Cu K\a'
   synchrotron 

_journal_data_validation_number
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_data_validation_number'
_type  char 
_type_conditions  none 

_diffrn_refln_wavelength
_category 'diffrn_refln'
_definition
 
;
The mean wavelength in angstroms of radiation used to measure
               the intensity of this reflection. This is an important parameter
               for reflections measured using energy dispersive detectors or the
               Laue method.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_diffrn_refln_index_'
_name '_diffrn_refln_wavelength'
_type  numb 
_type_conditions  none 
_units  A 
_units_detail  angstroms 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_audit_[]
_category 'category_overview'
_category.id  audit 
_definition
 
;
Data items in the AUDIT category record details about the
               creation and subsequent updating of the data block.
;

_list  no 
_name '_audit_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_audit_block_code                  TOZ_1991-03-20

    _audit_creation_date               1991-03-20
    _audit_creation_method             from_xtal_archive_file_using_CIFIO
    _audit_update_record
    ; 1991-04-09     text and data added by Tony Willis.
      1991-04-15     rec'd by co-editor as manuscript HL0007.
      1991-04-17     adjustments based on first referee report.
      1991-04-18     adjustments based on second referee report.
    ;
;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_atom_site_symmetry_multiplicity
_category 'atom_site'
_definition
 
;
The multiplicity of a site due to the space-group symmetry as is
               given in International Tables for Crystallography, Vol. A (1987).
;

_enumeration_range  1:192 
_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_symmetry_multiplicity'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   192.0   192.0 
   192.0   1.0 
   1.0   1.0 

_valence_param_atom_1
_category 'valence_param'
_definition
 
;
The element symbol of the first atom forming the bond whose
               bond valence parameters are given in this category.
;

_list  yes 
_list_reference '_valence_param_id'
_name '_valence_param_atom_1'
_type  char 
_type_conditions  none 

_reflns_limit_k_max
_category  reflns 
_definition
 
;
Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

_list  no 
_name '_reflns_limit_k_max'
_type  numb 
_type_conditions  none 

_computing_publication_material
_category  computing 
_definition
 
;
Software used in the processing of this data. Give the program
               or package name and a brief reference.
;

_list  no 
_name '_computing_publication_material'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
  'CAD-4 (Enraf-Nonius, 1989)'
  'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
  'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
  'CRYSTALS (Watkin, 1988)'
  'SHELX85 (Sheldrick, 1985)'

_citation_country
_category  citation 
_definition
 
;
The country of publication;  relevant for both journal articles
               and book chapters.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_country'
_type  char 
_type_conditions  none 

_publ_body_format
_category 'publ_body'
_definition
 
;
Code indicating the appropriate typesetting conventions
               for accented characters and special symbols in the text
               section.
;

_enumeration_default  cif 
_list  yes 
_list_reference '_publ_body_label'
_name '_publ_body_format'
_type  char 
_type_conditions  none 

 loop_
   _enumeration                                                               
   _enumeration_detail                                                        
   ascii  'no coding for special symbols'
   cif  'CIF convention'
   latex   LaTeX 
   rtf  'Rich Text Format'
   sgml  'SGML (ISO 8879)'
   tex   TeX 
   troff  'troff or nroff'

_chemical_formula_iupac
_category 'chemical_formula'
_definition
 
;
Formula expressed in conformance with IUPAC rules for inorganic
               and metal-organic compounds where these conflict with the rules
               for any other _chemical_formula_ entries. Typically used for
               formatting a formula in accordance with journal rules. This
               should appear in the data block in addition to the most
               appropriate of the other _chemical_formula_ data names.

               Ref: IUPAC (1990). Nomenclature of Inorganic Chemistry.
                    Oxford: Blackwell Scientific Publications.
;

_example '[Co Re (C12 H22 P)2 (C O)6].0.5C H3 O H'
_list  no 
_name '_chemical_formula_iupac'
_type  char 
_type_conditions  none 

_chemical_conn_bond_[]
_category 'category_overview'
_category.id 'chemical_conn_bond'
_definition
 
;
Data items in the _chemical_conn_atom_ and _chemical_conn_bond_
               categories record details about the 2D chemical structure of
               the molecular species. They allow a 2D chemical diagram to be
               reconstructed for use in a publication or in a database search
               for structural and substructural relationships.

               The _chemical_conn_bond_ data items specify the connections
               between the atoms in the _chemical_conn_atom_ list and the nature
               of the chemical bond between these atoms.
;

_list  no 
_name '_chemical_conn_bond_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _chemical_conn_bond_atom_1
    _chemical_conn_bond_atom_2
    _chemical_conn_bond_type
       4     1     doub     4     3     sing
       4     2     sing     5     3     sing
       6     5     sing     7     6     sing
       8     7     sing     8     3     sing
       10    2     sing     12    9     doub
       12    11    sing     12    10    sing
       13    11    sing     14    13    sing
       15    14    sing     16    15    sing
       16    11    sing     17    5     sing
       18    5     sing     19    6     sing
       20    6     sing     21    7     sing
       22    7     sing     23    8     sing
       24    8     sing     25    13    sing
       26    13    sing     27    14    sing
       28    14    sing     29    15    sing
       30    15    sing     31    16    sing
       32    16    sing
;
  
;
Example 1 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [(1996). Acta Cryst. C52, 951-953].
;
 

_refine_ls_restrained_S_all
_category  refine 
_definition
 
;
The least-squares goodness-of-fit parameter S' for all
               reflections after the final cycle of least squares. This
               parameter explicitly includes the restraints applied in the
               least-squares process. See also _refine_ls_goodness_of_fit_
               definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

_enumeration_range  0.0: 
_list  no 
_name '_refine_ls_restrained_S_all'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_melting_point_lt
_category  chemical 
_definition
 
;
A temperature in kelvins below which (*_lt) or above
               which (*_gt) the melting point, the temperature at which a
               crystalline solid changes to a liquid, lies. These items allow a
               range of temperatures to be given.

               _chemical_melting_point should always be used in preference
               to these items whenever possible.
;

_enumeration_range  0.0: 
_list  no 
_name '_chemical_melting_point_lt'
_related_function  alternate 
_related_item '_chemical_melting_point'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_orient_matrix_UB_13
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_13'
_type  numb 
_type_conditions  none 

_diffrn_orient_matrix_UB_12
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_12'
_type  numb 
_type_conditions  none 

_diffrn_orient_matrix_UB_11
_category 'diffrn_orient_matrix'
_definition
 
;
The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

_list  no 
_name '_diffrn_orient_matrix_UB_11'
_type  numb 
_type_conditions  none 

_journal_date_recd_hard_copy
_category  journal 
_definition 'Data items specified by the journal staff.'
_list  no 
_name '_journal_date_recd_hard_copy'
_type  char 
_type_conditions  none 

_diffrn_source_take-off_angle
_category 'diffrn_source'
_definition
 
;
The complement of the angle in degrees between the normal
               to the surface of the X-ray tube target and the primary
               X-ray beam for beams generated by traditional X-ray tubes.
;

_enumeration_range  0:90 
_example  1.53 
_list  no 
_name '_diffrn_source_take-off_angle'
_type  numb 
_type_conditions  none 
_units  degrees 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   90.0   90.0 
   90.0   0.0 
   0.0   0.0 

_geom_[]
_category 'category_overview'
_category.id  geom 
_definition
 
;
Data items in the GEOM and related (GEOM_ANGLE,
               GEOM_BOND, GEOM_CONTACT, GEOM_HBOND and GEOM_TORSION)
               categories record details about the molecular and crystal
               geometry, as calculated from the contents of the ATOM,
               CELL, and SYMMETRY data.

               Geometry data are usually redundant, in that they can be
               calculated from other more fundamental quantities in the data
               block. They serve, however, the dual purpose of providing a
               check on the correctness of both sets of data, and of enabling
               the most important geometric data to be identified for
               publication by setting the appropriate publication flag.
;

_list  no 
_name '_geom_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_geom_special_details
    ;  All esds (except the esd in the dihedral angle between
       two l.s. planes) are estimated using the full covariance
       matrix. The cell esds are taken into account individually
       in the estimation of esds in distances, angles and
       torsion angles; correlations between esds in cell
       parameters are only used when they are defined by crystal
       symmetry. An approximate (isotropic) treatment of cell esds
       is used for estimating esds involving l.s. planes.
    ;
;
  
;
Example 1 - based on data set bagan of Yamane & DiSalvo [(1996). Acta
                Cryst. C52, 760-761].
;
 

_reflns_number_gt
_category  reflns 
_definition
 
;
The number of reflections in the _refln_ list (not the
               _diffrn_refln_ list) that are significantly intense, satisfying
               the criterion specified by _reflns_threshold_expression. It may
               include Friedel equivalent reflections (i.e. those which are
               symmetry equivalent under the Laue symmetry but inequivalent
               under the crystal class) according to the nature of the
               structure and the procedures used. The special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details.
;

_enumeration_range  0: 
_list  no 
_name '_reflns_number_gt'
_related_function  alternate 
_related_item '_reflns_number_observed'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_chemical_conn_atom_charge
_category 'chemical_conn_atom'
_definition
 
;
The net integer charge assigned to this atom. This is the
               formal charge assignment normally found in chemical diagrams.
;

_enumeration_default  0 
_enumeration_range  -6:6 
_list  yes 
_list_reference '_chemical_conn_atom_type_symbol'
_name '_chemical_conn_atom_charge'
_type  numb 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   1  'for an ammonium nitrogen'
   -1  'for a chloride ion'

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   6.0   6.0 
   6.0   -6.0 
   -6.0   -6.0 

_atom_sites_Cartn_tran_matrix_21
_category 'atom_sites'
_definition
 
;
Matrix elements used to transform fractional coordinates in
               the ATOM_SITES category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

_list  no 
_name '_atom_sites_Cartn_tran_matrix_21'
_type  numb 
_type_conditions  none 

_geom_torsion_site_symmetry_3
_category 'geom_torsion'
_definition
 
;
The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _symmetry_equiv_pos_site_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

_list  yes 
_list_reference '_geom_torsion_atom_site_label_'
_name '_geom_torsion_site_symmetry_3'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   .  'no symmetry or translation to site'
   4  '4th symmetry operation applied'
  '7_645' '7th symm. posn.; +a on x; -b on y'

_refln_mean_path_length_tbar
_category  refln 
_definition
 
;
Mean path length in millimetres through the crystal for this
               reflection.
;

_enumeration_range  0.0: 
_list  yes 
_list_reference '_refln_index_'
_name '_refln_mean_path_length_tbar'
_type  numb 
_type_conditions  none 
_units  mm 
_units_detail  millimetres 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_atom_site_disorder_assembly
_category 'atom_site'
_definition
 
;
A code which identifies a cluster of atoms that show long range
               positional disorder but are locally ordered. Within each such
               cluster of atoms, _atom_site_disorder_group is used to identify
               the sites that are simultaneously occupied. This field is only
               needed if there is more than one cluster of disordered atoms
               showing independent local order.
;

_list  yes 
_list_reference '_atom_site_label'
_name '_atom_site_disorder_assembly'
_type  char 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
   A  'disordered methyl assembly with groups 1 and 2'
   B  'disordered sites related by a mirror'
   S  'disordered sites independent of symmetry'

_diffrn_source_voltage
_category 'diffrn_source'
_definition
 
;
The voltage in kilovolts at which the radiation source was
               operated.
;

_enumeration_range  0.0: 
_list  no 
_name '_diffrn_source_voltage'
_type  numb 
_type_conditions  none 
_units  kV 
_units_detail  kilovolts 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_scale_group_[]
_category 'category_overview'
_category.id 'diffrn_scale_group'
_definition
 
;
Data items in the DIFFRN_SCALE_GROUP category record details
               of the scaling factors applied to place all intensities in
               the reflection lists on a common scale.

               Scaling groups might, for instance, correspond to each film
               in a multi-film data set, or each crystal in a multi-crystal
               data set.
;

_list  no 
_name '_diffrn_scale_group_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
loop_
    _diffrn_scale_group_code
    _diffrn_scale_group_I_net
      1    .86473
      2   1.0654
;
  'Example 1 - hypothetical example.'

 loop_
   _category_mandatory.name                                                   
  '_diffrn_scale_group_code'

_reflns_shell_Rmerge_F_obs
_category 'reflns_shell'
_definition
 
;
The value of Rmerge(F) for reflections classified as 'observed'
               (see _reflns_observed_criterion) in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

_enumeration_range  0.0: 
_list  yes 
_name '_reflns_shell_Rmerge_F_obs'
_related_function  replace 
_related_item '_reflns_shell_Rmerge_F_gt'
_type  numb 
_type_conditions  none 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_diffrn_[]
_category 'category_overview'
_category.id  diffrn 
_definition
 
;
Data items in the DIFFRN category record details about the
               intensity measurements.
;

_list  no 
_name '_diffrn_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_diffrn_special_details
    ;  \q scan width (1.0 + 0.14tan\q)\%, \q scan rate 1.2\% min^-1^.
       Background counts for 5 s on each side every scan.
    ;

    _diffrn_ambient_temperature         293

;
  
;
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [(1991).
                Acta Cryst. C47, 2276-2277].
;
 

_audit_conform_[]
_category 'category_overview'
_category.id 'audit_conform'
_definition
 
;
Data items in the AUDIT_CONFORM category describe the
               dictionary versions against which the data names appearing in
               the current data block are conformant.
;

_list  no 
_name '_audit_conform_[]'
_type  null 
_type_conditions  none 

 loop_
   _example                                                                   
   _example_detail                                                            
  
;
_audit_conform_dict_name         cif_core.dic
    _audit_conform_dict_version      2.3
    _audit_conform_dict_location     ftp://ftp.iucr.org/pub/cif_core.2.3.dic
;
  'Example 1 - Any file conforming to the current CIF core dictionary.'

 loop_
   _category_mandatory.name                                                   
  '_audit_conform_dict_name'

_exptl_crystal_density_meas_temp_lt
_category 'exptl_crystal'
_definition
 
;
Temperature in kelvins above which (*_gt) or below which
               (*_lt) _exptl_crystal_density_meas was determined. These
               items should not be used for reporting new work where the
               correct temperature of measurement should be given. They are
               intended for use in reporting information stored in databases
               or archives which would be misleading if reported under
               _exptl_crystal_density_meas_temp.
;

_enumeration_range  0.0: 
_list  both 
_list_reference '_exptl_crystal_id'
_name '_exptl_crystal_density_meas_temp_lt'
_related_function  alternate 
_related_item '_exptl_crystal_density_meas_temp'
_type  numb 
_type_conditions  none 
_units  K 
_units_detail  kelvin 

 loop_
   _example                                                                   
   _example_detail                                                            
  '_exptl_crystal_density_meas_temp_lt   300' 
;
The density was measured at some unspecified
                                temperature below room temperature.
;
 

 loop_
   _item_range.maximum                                                        
   _item_range.minimum                                                        
   .   0.0 
   0.0   0.0 

_citation_book_title
_category  citation 
_definition
 
;
The title of the book in which the citation appeared;  relevant
               for book chapters.
;

_list  yes 
_list_reference '_citation_id'
_name '_citation_book_title'
_type  char 
_type_conditions  none 

_atom_site_aniso_U_22
_category 'atom_site'
_definition
 
;
These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure factor term:

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

_list  yes 
_list_reference '_atom_site_aniso_label'
_name '_atom_site_aniso_U_22'
_related_function  conversion 
_related_item '_atom_site_aniso_B_'
_type  numb 
_type_conditions  esd 
_units  A^2^ 
_units_detail 'angstroms squared'

_database_code_PDF
_category  database 
_definition
 
;
The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural (organic and metal-organic compounds);
               Inorganic Crystal Structure; Metals Data File (metal structures);
               NBS (NIST) Crystal Data Database (lattice parameters); Protein
               Data Bank; and the Powder Diffraction File (JCPDS/ICDD).
;

_list  no 
_name '_database_code_PDF'
_type  char 
_type_conditions  none 

_atom_site_aniso_label
_category 'atom_site'
_definition
 
;
Anisotropic atomic displacement parameters are usually looped in
               a separate list. If this is the case, this code must match the
               _atom_site_label of the associated atom coordinate list and
               conform with the same rules described in _atom_site_label.
;

_list  yes 
_list_link_parent '_atom_site_label'
_list_mandatory  yes 
_name '_atom_site_aniso_label'
_type  char 
_type_conditions  none 

_diffrn_measurement_method
_category 'diffrn_measurement'
_definition 'Method used to measure intensities.'
_example 'profile data from \q/2\q scans'
_list  no 
_name '_diffrn_measurement_method'
_type  char 
_type_conditions  none 
