Berto 'd Sera wrote:
Both domains seem to be up and running, Brion has been quick :)
Note that there is an IETF mailing list and IANA registration authority for "language subtags", as specified in RFC 4645, 4646, and 4647. These RFC are updating RFC 3066, which is the Internet's equivalent to ISO 3166.
For example, the German spelling reform of 1996 created a need in some instances to tell the old spelling (following Duden's dictionary from 1901) apart from the new one (after the 1996 reform). Thus, the language subtags de-1901 and de-1996 have been registered as official code names for the two German orthographies.
This is to say that there is a way to register an official subtag for "old" Byelorussian (instead of the inofficial be-x-old), if the speakers of that language can agree on a suitable subtag. As always, your chances to succeed are greatest if you are well prepared and already have a consensus within your community.
IANA registry, http://www.iana.org/assignments/language-subtag-registry
IETF mailing list, http://www.alvestrand.no/mailman/listinfo/ietf-languages