IUCr Crystallographic Information Framework

The International Union of Crystallography is the sponsor of the Crystallographic Information Framework, a standard for information interchange in crystallography.


The acronym CIF is used both for the Crystallographic Information File, the data exchange standard file format of Hall, Allen & Brown (1991) (see Documentation), and for the Crystallographic Information Framework, a broader system of exchange protocols based on data dictionaries and relational rules expressible in different machine-readable manifestations, including, but not restricted to, Crystallographic Information File and XML.


Formal specification of the Crystallographic Information File format

Ancillary notes

Documentation on CIF



The Committee for the Maintenance of the CIF Standard oversees the development of the Crystallographic Information Framework and reports to the Executive Committee of the IUCr.

Dictionary Definition Languages

Attributes of canonical data descriptors in CIF are described by a machine-readable definition language (DDL).

Current CIF Dictionaries

Canonical data descriptors and their attributes are presented in machine-readable data dictionaries.

Descriptors for small-molecule, inorganic and other small-unit-cell structures

Descriptors for macromolecular structures and other DDL2-based dictionaries