CIF DATA FOR INTERNATIONAL TABLES FOR CRYSTALLOGRAPHY; VOL: A1 [SUBGROUP DATA] (TO APPEAR) AND VOL: A. Wondratschek, H.; Institut fuer Kristallographie, Universitaet, D-76128 Karlsruhe, Germany; Madariaga, G. and Aroyo, M. I., Dpto. de Fisica de la Materia Condensada, Facultad de Ciencias, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Spain

This contribution deals with the inclusion of:

(i) the complete information on subgroups of space groups [International Tables for Crystallography Vol. A1], (to appear)

(ii) the symmetry information of International Tables for Crystallography, Vol. A (IT A) into the CIF format.

The proposed block structure follows closely the arrangement of the symmetry information in IT A. To each subgroup a number of blocks is assigned such that each block contains some aspect of the space-group data. Each subgroup is described in one separate block. Provisions are made for a future expansion of the data, e.g. for information on supergroups of space groups which is not available at present.

For the extension of the existing CIF-core dictionary a list of data names is being proposed which refer to the different entries of IT A and the specific requirements of the subgroup tables.

The complete list of subgroups of the space groups Cc (No. 9) and P3221 (No. 154) as well as part of the data of IT A will be displayed in the proposed CIF format. The information concerning these two examples has been extracted from a CIF master file which already exists. Some simple tools for applications will be demonsated.

This version of an extension of the CIF Dictionary should be considered as a draft presented for approval to the IUCr Committee for the Maintenance of the CIF Standard. When this proposal has been accepted the data files can be supplied in due course.