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Appendix B. Identifiers
The ANSI/NISO standard addresses the need for proper names in a thesaurus: these
“may be assigned to content objects identifiers, differentiated from topical terms”
(ANSI/NISO Z39.19-2005, §6.6.7). Identifiers for people and places fall outside the
scope of the TGDT, but in consideration of its special emphasis on practice, it lists iden-
tifiers for selected instances of four important open-ended classes of identifiers not nor-
mally considered for inclusion in a thesaurus: typefaces, languages, software, and file
formats. In addition, provision is made for creating identifiers for individual characters
within the Unicode character set.
The TGDT distinguishes these identifiers by listing them in italics within square
brackets – for example, the French language is listed as [French (language) ].
Because these identifiers are considered to fall outside the preferred terminology of
the the TGDT proper, they are not assigned classification notations of their own; instead,
the notation for their parent terms may be used with a plus sign (‘+’) appended, followed
by a suitable code as discussed below, if one is available.
Class Identifier Classification notation
Base Qualifier Base + Extension
Typefaces Commonly accepted
name of the typeface
typeface C.44.74.90 + No recommendation
Characters Unicode character
name
character C.44.13.90 + Unicode hexadeci-
mal character code
Languages SIL Ethnologue pri-
mary name
language C.79.9 + SIL Ethnologue
three-letter code
Software Manufacturer’s name
for the software, pre-
ceded by the manu-
facturer’s name if
needed
software C.27.62.9 + No recommendation
File formats Commonly accepted
name (may be an
acronym)
file format C.27.10.30.6 + Commonly used
acronym or initial-
ism
Table 1. Summary of identifier classes.
Table 1 summarizes the recommended practice in constructing identifiers and their clas-
sification notations.