Right on time!

This conversation comes up once a year usually around this time:
Oct 27, 2009 - "ISO 639-3"
Jan 24, 2010 - "ISO 639 (was Re: Introduction to software localisation
for conlangers)"
Sep 22, 2011 - "Extending ISO 639 for conlangs?"
Oct 18, 2012 - "Extensible Language Codes?"

There is a ConLang Code Registry that assigns codes from the "reserved
for local use" area to conlangs:

Of the people who actually care enough to use ISO 639 codes for
conlangs, some support using local use codes, but most seem to prefer
using the "xx" code with some system for specifying the language using
an extension, like "xx-mikiana" or "xx-rgb-mikiana". They usually cite
the limited number of codes and the potential of a land-grab as a
reason to use "xx" instead of "qaa"-"qtz". I continue to believe a
shortage of codes is unlikely, given that few people care enough.

-- Rebecca Bettencourt

On Thu, Oct 18, 2012 at 10:39 PM, Logan Kearsley <[log in to unmask]> wrote:
> I recall some time ago a conversation on the list about those 2-and-3
> letter language abbreviation codes (e.g., ISO 639-3
>, and how there was some
> convention for specifying extensions or special-use codes (kinda like
> "*/vnd.*"  mime types or "X-" http headers). I cannot now find that
> conversation nor any relevant standards documents; does anybody know
> what I'm talking about, or where I might find such information? I
> recently find myself in the midst of two different projects which
> require the use of language codes and would benefit from not being
> restricted to a list of previously studied natural languages.
> -l.