IUCr 1999 Triennial Report - Report of Committee for the Maintenance of the Crystallographic Information File (COMCIFS)


The purpose of COMCIFS is to commission and approve new CIF dictionaries and to keep the crystallographic community informed of its decisions. COMCIFS is a Sub-committee of the Executive Committee.


The members of COMCIFS during the triennium were: I.D. Brown (Chair), P.R. Edgington, P.M.D. Fitzgerald, S.R. Hall, G. Madariaga, B. McMahon (Secretary), M.A. Spackman, B.H. Toby. In addition, COMCIFS has had a number of consultants and observers who have received COMCIFS mailings and made important contributions to the discussions.

Approval of dictionaries

During the triennium, three dictionaries were approved, one was a revision and two were new. These were:

The second version of the core dictionary (core_cif.dic 2.0), which is used, inter alia, for submission of papers to Acta Cryst. Section C.

The dictionary for macromolecular structures (mm_cif.dic 1.0), which is being adopted by the Protein Databank and the Nucleic Acid Databank.

The dictionary for powder diffraction (pd_cif.dic 1.0), which is being adopted for the Powder Diffraction File.

Support for these dictionaries is provided by Dictionary Maintenance Groups chaired by I.D. Brown (core_cif.dic), P.M.D. Fitzgerald (mm_cif.dic) and B.H. Toby (pd_cif.dic). These groups are charged with consulting with their respective communities and preparing revised versions of the dictionaries as required.

Revisions proposed by the Dictionary Maintenance Groups are presented to COMCIFS for final approval. Revised versions of the core (2.1) and macromolecular (1.1) dictionaries are at an advanced stage.

Preparation of new dictionaries

Six new dictionaries are in various stages of preparation. These are:

A modulated structure dictionary (ms_cif.dic) which will be shortly presented to COMCIFS for tentative approval. It is being prepared by a group under the direction of G. Madariaga.

A dictionary for images (img_cif.dic) which is also nearly ready for presentation to COMCIFS for tentative approval. This is designed for storing diffraction patterns from two-dimensional detectors, but it will be able to store any two-dimensional image with extension to higher dimensions. Because of the size of the files and the need to process them in real time, a binary version of this CIF is also being defined. The ASCII and binary standards are identical except for differences needed to write and read a binary file. A. Hammersley is in charge of this project.

A small-angle scattering dictionary (sas_cif.dic), which is being constructed by a group headed by M. Malfois. A draft has been prepared.

A dictionary for magnetic structures (mag_cif.dic), which is being prepared in conjunction with the Database of Magnetic Structures Determined by Neutron Diffraction, headed by W. Sikora.

A dictionary for crystallographic symmetry (sym_cif.dic), which is under construction by a group headed by I.D. Brown.

A dictionary for electron density CIFs (rho_cif.dic), which, after a slow start, is being prepared by a group under P. Mallinson.


All COMCIFS formal business is conducted via an electronic discussion group whose transactions can be viewed by the public at http://www.iucr.org/iucr-top/lists/comcifs-l. In addition, regular reports on COMCIFS activity have appeared in the IUCr Newsletter.

Other Projects

A group is exploring questions of intellectual property rights related to CIFs and CIF-based software.

We are also working on a scheme to allow the automatic concatenation of different dictionaries at run time in order to allow one dictionary to incorporate other dictionaries that may be necessary for its proper functioning. This raises the question of whether we should continue to carry the overhead of maintaining CIF dictionaries in two incompatible Dictionary Definition Languages (DDL) or whether we should standardise on one DDL.

Proposals are being prepared which may allow dictionaries to express functional relationships between the different archived items.


It is my pleasure to thank the members of the committee, and others too numerous to mention, whose careful and often time-consuming efforts have made an essential contribution to the success of CIF.

I.D. Brown, Chair

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Updated 6th June 1999