Section 1.1.7. The Crystallographic Information File

As outlined in Section 1.1.6, the working group commissioned by the WPCI set out to establish an exchange protocol suitable for submitting crystallographic data to journals and databases, and this resulted in the development of the CIF syntax. At the same time, the group was also asked to form a list of those data items considered to be essential in a manuscript submitted to Acta Crystallographica. The data items originally recommended are listed in Fig. 1.1.7.1.

Figure 1.1.7.1 | top | pdf | Initial set of data items considered to be essential in a structure report submitted to Acta Crystallographica Section C.

The syntax of a CIF (a detailed description is given in Chapter 2.2 ) was intentionally a simple subset of the STAR File syntax (see Chapter 2.1 for details). This simplification was considered important for its easy implementation in existing crystallographic software packages – clearly a primary goal for any format that was to be widely available for submitting data to journals and databases.

A compilation of data names referring to specific quantities or concepts in a crystal-structure determination was drawn up. This compilation included the items already identified as necessary for publication and many more besides. As a list of standard tags intended for unambiguous use, the collection was known from the outset as a dictionary of data names.

The WPCI proposed the CIF format as a standard exchange protocol at the open meetings of the IUCr Commissions on Crystallographic Data and Computing at the 1990 XVth IUCr Congress in Bordeaux. The proposal was accepted and the CIF format was subsequently adopted by the IUCr as the preferred format for data exchange (Hall et al., 1991).

The administration of the CIF standard, including the approval of new data items, is the responsibility of the IUCr Committee for the Maintenance of the CIF Standard (COMCIFS). This committee plays a central role in the coordination of CIF activities, such as the creation of new dictionaries for defining crystallographic data items and the updating of data definitions in existing dictionaries. Chapter 3.1 describes relevant aspects of its role in the commissioning and maintenance cycle. Information about COMCIFS activities and other CIF developments may be obtained from http://www.iucr.org/iucr-top/cif/ .