I recall some time ago a conversation on the list about those 2-and-3 letter language abbreviation codes (e.g., ISO 639-3 http://www.sil.org/iso639-3/codes.asp), 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.