I note with interest that ccTLDs make use of ISO 3166 in spite of its potential for instability. In the case of ccTLDs, however, there is a considerable infrastructure for dealing with this: the DN system and strict procedures for deploying changes in ccTLDs onto domains. In the case of language tags, there are no such procedures for deploying changes in meanings of country identifiers across instances of metadata elements used to declare linguistic properties of information objects, nor is anything of that sort feasible in the general case. It may be that in the context of certain Internet protocols it is feasible to deploy changes in ISO 3166 across instances of language tags used by those protocols -- I don't know if this is true for any Internet protocols or not. It is certainly not true of all applications of ISO 639 standards that also make use of ISO 3166.
Dear Peter,
This is a very good documentation of the reason why the reference is not the ISO 3166, but the ccTLDs' reading (ie. RFC 1591). As the languages and users are not something which change in a possibly changing world, the ccTLD list is the best updated list to be used. Because it is directly in tune with the life of the world (in addition to be the one which references the IDNs, if they are ever used - which are necessary to call and use language web pages). Anyway any reference to IANA should recall that the IANA is now - like it or not - an ICANN function. I do not necessarily like an ICANN governance and prefer a global intergovernance, but I acknowledge that someone has to maintain the real life lists.
Now, I am afraid you did not consider OPES (RFC 3914 - 3897 - 3838 - 3837 - 3836 - 3835 - 3752 and IAB RFC3238) and their capabilities as interstandard adapters. Please reread RFC 1958: only one principle will never change: that everything else will change.
Let assume that I use my documented generalized language tag script-variation.language-dialect.country-area.type_of_application.authority, with different language matching algorithms, on an OPES server. I have no problem to serve all your W3C applications with all the RFC 3066nth like variation perfectly fitting tags (that is, if I know which "nth" brand you want), and MPEG, and etc. and may be to translate content accordingly (this is exactly the intent).
jfc
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