I think the main structure of the tagging should now be:
<Language>-<Variant>
where <Language> may be:
- an ISO 639 language code (of whatever version; make a note that
3-letter languages are expected in a later ISO 639 version)
- The single letter "X" for private extensions
- The four-letter string "IANA" for IANA registered extensions
I bet my 0.001 Yen that, in the future version of ISO 639, language names
"X" or "IANA" will be registered.
To Ohta-san: This is the way we always work, I think:
I know what is your work.
Building little
pieces on top of other pieces, so that we can get our work done.
Nothing new in that.
Building large piece of documents on top of other already huge pieces and
your work is done. The implementation is someone else's problem, of course.
I'm afraid you don't mind if thw work is useful only for the group of
proffessional Linguists who shares a single doctrine of linguistics.
Masataka Ohta