Crystallographic Information Framework

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Macromolecular dictionary (mmCIF) version 2.0.09




   Contains all the data items that refer to the space group as a
   whole, such as its name or crystal system. They 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
   this dictionary.  The remainder are found in the symmetry CIF

   Space-group types are identified by their number as given in
   International Tables for Crystallography Vol. A. 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. A Hermann-Mauguin
   symbol 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 symmetry CIF dictionary.


Example 1 - the monoclinic space group No. 15 with unique axis b.                 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

Category key:

Mandatory category: no