Chapter 2.2 Specification of the Crystallographic Information File (CIF)

Definition and exchange of crystallographic data

First Online Edition (2006)

Part 2. Concepts and specifications

  1. S. R. Hall1,
  2. J. D. Westbrook2,
  3. N. Spadaccini3,
  4. I. D. Brown4,
  5. H. J. Bernstein5,
  6. B. McMahon6

Published Online: 1 JAN 2006

DOI: 10.1107/97809553602060000728

International Tables for Crystallography

International Tables for Crystallography

How to Cite

Hall, S. R., Westbrook, J. D., Spadaccini, N., Brown, I. D., Bernstein, H. J. and McMahon, B. 2006. Specification of the Crystallographic Information File (CIF). International Tables for Crystallography. G:2:2.2:20–36.

Author Information

  1. 1

    School of Biomedical and Chemical Sciences, University of Western Australia, Crawley, Perth, WA 6009, Australia

  2. 2

    Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers, The State University of New Jersey, Department of Chemistry and Chemical Biology, 610 Taylor Road, Piscataway, NJ 08854-8087, USA

  3. 3

    School of Computer Science and Software Engineering, University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia

  4. 4

    Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L8S 4M1

  5. 5

    Department of Mathematics and Computer Science, Kramer Science Center, Dowling College, Idle Hour Blvd, Oakdale, NY 11769, USA

  6. 6

    International Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England

Publication History

  1. Published Online: 1 JAN 2006


The Crystallographic Information File (CIF) is an electronic file containing specific data items relevant to crystallographic structure determinations and descriptions in the form of numbers and text, which are represented as ASCII character strings. The structure and format of a CIF are based on a restricted subset of the syntax of a Self-defining Text Archive and Retrieval (STAR) File. The CIF is intended as a general, flexible and extensible free-format file suitable for the transmission, storage and publication of crystallographic data. Since 1990 it has been recommended by the International Union of Crystallography as the preferred data structure for the exchange of data. This chapter provides a detailed description of the syntax features of a CIF and its conventions for associating meaning or semantic content to included data. Particular care is taken to describe how the file format handles issues of portability and archival integrity. The chapter includes the complete official specification, and a formal grammar in extended Backus–Naur form.


  • CIF specification;
  • Crystallographic Information File specification;
  • data names;
  • data values;
  • data items;
  • data blocks;
  • block codes;
  • looped lists;
  • CIF syntax;
  • Crystallographic Information File syntax;
  • CIF grammar;
  • Crystallographic Information File grammar;
  • character sets;
  • line terminators;
  • line lengths;
  • case sensitivity;
  • semantics;
  • data types;
  • encoding;
  • metadata;
  • save frames;
  • name spaces;
  • special characters;
  • frame codes