The Crystallographic Information File

Version 1.1 Working specification

The Crystallographic Information File (CIF) is an archiving and information interchange standard for crystallographic and related structural science data promoted by the International Union for Crystallography. It is a restricted-syntax implementation of the general Self-Defining Text Archival and Retrieval (STAR) File format (Hall, 1991; Hall & Spadaccini, 1994). Names and attributes of standard data items are defined in publicly available collections known as data dictionaries under the authority of an IUCr Committee (COMCIFS).

Conformance

Any file claiming to be a crystallographic information file must conform to the specifications as herein laid out. Since CIF is an extensible format, files may be considered valid where they contain syntactically legal extensions to content beyond the standard data items as defined in public dictionaries. It is also inevitable that CIF software will be written to exploit various subsets of the information that may be conveyed in a CIF, and therefore not all software will be required to handle all content in a specific manner.

However, all CIF conformant software must as a minimum be able to locate, extract or write data items in strict accordance with the syntax rules that form part of this specification.

• File syntax
• Common semantic features

Version history

• Version 1.1 Draft of 27 September 2002; approved by COMCIFS as working specification 10 December 2002; posted on IUCr web 24 February 2003.
• Minor editorial changes to wording during Volume G editorial review. 30 May 2002 - B. McMahon
• Line-folding example of semantics document para 26 corrected. 3 August 2004 - B. McMahon
• Statement about ordering of data items introduced in para 7; ambiguity regarding treatment of global_ removed from para 55. 4 March 2005 - B. McMahon
• Version 1.0 Retrospective labelling of version described in original paper of Hall, Allen & Brown (1991), as amended by COMCIFS 29 January 1997.

References

• Hall, S. R. (1991). "The STAR File: A New Format for Electronic Data Transfer and Archiving", J. Chem. Inform. Comp. Sci., 31, 326-333.
• Hall, S. R., Allen, F. H. and Brown, I. D. (1991). "The Crystallographic Information File (CIF): A New Standard Archive File for Crystallography", Acta Cryst., A47, 655-685 See also HTML version (http://www.iucr.org/iucr-top/cif/standard/cifstd1.html)
• Hall, S.R. & Spadaccini, N. (1994). "The STAR File: Detailed Specifications," J. Chem. Info. Comp. Sci., 34, 505-508.