Core dictionary (coreCIF) version 2.4.5
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 the core dictionary. The remainder are found in the symmetry CIF dictionary. 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:
Example 1 - the monoclinic space group No. 15 with unique axis b.
_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