CIF specification: reserved prefixes
Sydney R Hall syd at crystal.uwa.edu.auWed Oct 29 08:31:57 GMT 2003
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Brian: Your change is logical and imposes no real constraints on reserved data name prefixes. I support it. Syd On Tuesday, October 28, 2003, at 08:06 PM, Brian McMahon wrote: > Dear Colleagues > > While working through the content of International Tables Volume G, I > have > come upon two statements that are in flat contradiction. In the CIF > specification, regarding the use of registered prefixes to reserve a > namespace of data items for local use, it is stated: > > > \P 12. There is no syntactic property identifying such a reserved > prefix, so that software validating or otherwise handling > such local data names must scan the entire registry and > match registered prefixes against the indicated components > of data names. Note that reserved prefixes may themselves > contain underscore characters, so a maximal matching search > must be made. > > while in chapter 3.1, "General considerations when defining a CIF data > item", I find I have written > > 3.1.2.2. Reserved prefixes > > 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 the preceding section, 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). > > I can in fact see no useful purpose in permitting an underscore > *within* a > registered prefix - it simply complicates the task of the parser. At > this > stage no prefixes have been registered with an embedded underscore. I > therefore propose to amend paragraph 12 of the CIF working spec, > replacing > the final sentence by > > "Note that reserved prefixes may not themselves contain underscore > characters." > > Please let me have your opinions on this as quickly as possible. I > shall > continue to work on the Volume on the assumption that no objections > will be > raised to this amendment. > > Regards > Brian > _______________________________________________ > comcifs mailing list > comcifs at iucr.org > http://scripts.iucr.org/mailman/listinfo/comcifs > > ------ Head at biomedchem.uwa.edu.au ,-_|\ Professor Sydney R. Hall Syd.Hall at bcs.uwa.edu.au / \ Head, School Biomed & Chem Sciences Fx: 61(8)9380 7330 --> *_,-._/ Faculty of Life & Physical Sciences Ph: 61(8)9380 2725 v University of Western Australia www.biomedchem.uwa.edu.au Crawley, 6009 AUSTRALIA.
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