Don't know if this is relevant to the discussion, but each SLP protocol
request includes a language tag that indicates which natural language the
attributes of the sought-after advertisements should be in. If the directory
agent supports the service type but not in the language of the request, then it
returns a LANGUAGE_NOT_SUPPORTED error. According to Erik Guttman, this makes
SLP conformant to RFC 2277.
In addition, draft-ietf-svrloc-service-scheme-13.txt, the standards
document describing how SLP service templates are standardized,
states that a service template must be submitted with an indication
of the natural language with which the template was composed. The
language does not show up in the template itself because the language
is part of the service advertisement when registered.
That said, there is no way to browse the set of languages
supported by the DA. Nor can a client find out from the set of
attributes what their natural language is. So if that kind of information
is important for the attributes (say for a Web search engine that
returns results in different languages) then it should by all means
be included in the attributes.