Crystallographic Information Framework

[CIF logo]

The IUCr policy for the protection and the promotion of the STAR File and CIF standards for exchanging and archiving electronic data


The Crystallographic Information File (CIF)[1] is a standard for information interchange promulgated by the International Union of Crystallography (IUCr). CIF (Hall, Allen & Brown, 1991) is the recommended method for submitting publications to Acta Crystallographica Section C and reports of crystal structure determinations to other sections of Acta Crystallographica and many other journals. The syntax of a CIF is a subset of the more general STAR File[2] format. The CIF and STAR File approaches are used increasingly in the structural sciences for data exchange and archiving, and are having a significant influence on these activities in other fields.

Statement of intent

The IUCr's interest in the STAR File is as a general data interchange standard for science, and its interest in the CIF, a conformant derivative of the STAR File, is as a concise data exchange and archival standard for crystallography and structural science.

Protection of the standards

To protect the STAR File and the CIF as standards for interchanging and archiving electronic data, the IUCr, on behalf of the scientific community,
  • holds the copyrights on the standards themselves,
  • owns the associated trademarks and service marks, and
  • holds a patent on the STAR File.
These intellectual property rights relate solely to the interchange formats, not to the data contained therein, nor to the software used in the generation, access or manipulation of the data.

Promotion of the standards

The sole requirement that the IUCr, in its protective role, imposes on software purporting to process STAR File or CIF data is that the following conditions be met prior to sale or distribution.
  • Software claiming to read files written to either the STAR File or the CIF standard must be able to extract the pertinent data from a file conformant to the STAR File syntax, or the CIF syntax, respectively.
  • Software claiming to write files in either the STAR File, or the CIF, standard must produce files that are conformant to the STAR File syntax, or the CIF syntax, respectively.
  • Software claiming to read definitions from a specific data dictionary approved by the IUCr must be able to extract any pertinent definition which is conformant to the dictionary definition language (DDL)[3] associated with that dictionary.
The IUCr, through its Committee on CIF Standards, will assist any developer to verify that software meets these conformance conditions.

Glossary of terms

[1] CIF:
is a data file conformant to the file syntax defined at
[2] STAR File:
is a data file conformant to the file syntax defined at
[3] DDL:
is a language used in a data dictionary to define data items in terms of "attributes". Dictionaries currently approved by the IUCr, and the DDL versions used to construct these dictionaries, are listed at

Last modified: 30 September 2000