Tables for
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G. ch. 3.1, pp. 74-75

Section 3.1.3. Formal definition process

B. McMahona*

aInternational Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England
Correspondence e-mail:

3.1.3. Formal definition process

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This section describes the formal system for creating public dictionaries or appending to them. It includes information on the review and approval cycles currently required by COMCIFS, which could change if these procedures are modified. The IUCr web page ( ) should be consulted for current practice. However, a short overview of the existing procedures is helpful in describing how the community can participate in extending the standard. Dictionary maintenance groups

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Each published dictionary authorized by COMCIFS has a group of specialists appointed or invited to extend and maintain the dictionary to serve the changing needs of the subdiscipline that sponsors the dictionary. Members of these dictionary maintenance groups (DMGs) may suggest extensions or corrigenda on their own initiative or may pass on requests for extensions from individual crystallographers. A DMG will typically debate and review any suggested amendments and produce a draft revised dictionary for approval by COMCIFS. mmCIF review cycle

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The macromolecular CIF dictionary covers a very broad and active field, and a more formal procedure exists for the submission and review of proposed extensions. Possible new definitions are submitted using pro forma dictionary templates to a member of an editorial board appointed by the mmCIF dictionary maintenance group. Accepted proposals are approved by the DMG and released for general community review in provisional extension dictionaries as circumstances require. The extension dictionary is revised as necessary and is finally incorporated within the parent mmCIF dictionary after COMCIFS approval has been granted. New dictionaries

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A completely new dictionary to cover a subdiscipline not otherwise catered for may be commissioned by COMCIFS or may arise from community action, occasionally sponsored by an IUCr Commission. A working group is appointed to create the dictionary and relevant example files or software. The working group is expected to test the new dictionary extensively within its own community before submitting it to COMCIFS for initial approval. It is the responsibility of COMCIFS to check the dictionary for technical consistency and for compatibility with related dictionaries. COMCIFS may refer the dictionary back to the working group for further revisions. When the dictionary finally receives formal COMCIFS approval and is published, a dictionary maintenance group is formed to promote its further development (Section[link]). The DMG usually includes one or more members of the initial working group and at least one voting member of COMCIFS.

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