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International
Tables for Crystallography Volume G Definition and exchange of crystallographic data Edited by S. R. Hall and B. McMahon © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. G. ch. 2.2, p. 25
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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.
