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

International Tables for Crystallography (2006). Vol. G, ch. 2.2, p. 25

Section 2.2.7.1.2. Definition of terms

S. R. Hall,a* N. Spadaccini,c I. D. Brown,d H. J. Bernstein,e J. D. Westbrookb and B. McMahonf

2.2.7.1.2. Definition of terms

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(2) The following terms are used in the CIF specification documents with the specific meanings indicated here.

(2.1) A CIF is a file conforming to the specification herein stated, containing either information on a crystallographic experiment or its results (or similar scientific content), or descriptions of the data identifiers in such a file.

(2.2) A data file is understood to convey information relating to a crystallographic experiment.

(2.3) A dictionary file is understood to contain information about the data items in one or more data files as identified by their data names.

(2.4) A data name is a case-insensitive identifier (a string of characters beginning with an underscore character) of the content of an associated data value.

(2.5) A data value is a string of characters representing a particular item of information. It may represent a single numerical value; a letter, word or phrase; extended discursive text; or in principle any coherent unit of data such as an image, audio clip or virtual-reality object.

(2.6) A data item is a specific piece of information defined by a data name and an associated data value.

(2.7) A tag is understood in this document to be a synonym for data name.

(2.8) A data block is the highest-level component of a CIF, containing data items or save frames. A data block is identified by a data-block header, which is an isolated character string (that is, bounded by white space and not forming part of a data value) beginning with the case-insensitive reserved characters data_.

(2.9) A block code is the variable part of a data-block header, e.g. the string foo in the header data_foo.

(2.10) A save frame is a partitioned collection of data items within a data block, started by a save-frame header, which is an isolated character string beginning with the case-insensitive reserved characters save_, and terminated with an isolated character string containing only the case-insensitive reserved characters save_.

(2.11) A frame code is the variable part of a save-frame header, e.g. the string foo in the header save_foo.








































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