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. 3.1, p. 74
Section 3.1.2.2. Reserved prefixes
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International Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England |
To guarantee that locally devised data names may be placed without name conflict in interchange data files, authors may register a reserved character string for their sole use. As with the special prefix _[local]_ discussed in Section 3.1.2.1, the author's reserved prefix is simply an underscore-bounded string within the data name (i.e. it may not itself include an underscore character). For DDL1 applications it must be the first component of the data name; for DDL2 applications it forms the first component of the data name if describing data names in a category not defined in the official dictionaries; or the first component after the full stop (category delimiter) if the local data name is an extension to an existing category.
Prefixes may be registered online through a web form at http://www.iucr.org/iucr-top/cif/spec/reserved.html
. Table 3.1.2.1 gives a list of prefixes registered as of March 2005; this list will of course go out of date, but a current list will be maintained on the web at the address above.
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An example of a data name incorporating a reserved prefix is the listing of a protein amino-acid sequence recorded temporarily by the Protein Data Bank before a protein structure is released, _pdbx_prerelease_seq.seq_one_letter_code.