(changed title so as not to confuse future readers)
Is this an authoritative list of languages I can use for my application?
From: http://en.wikipedia.org/wiki/ISO_639-1 –> http://www.infoterm.info/standardization/iso_639_1_2002.php
ISO Language Codes
ISO 639-1:2002
Codes for the representation of names
of languages — Part 1: Alpha-2 codeInfoterm has been designated the
Registration Authority (ISO 639-1/RA)
for the language alpha-2 language code
contained in ISO 639-1:2002 “Codes for
the representation of names of
languages – Part 1: Alpha-2 code /
Codes pour la représentation des noms
de langue – Partie 1 : Code alpha-2”.
-1 is old. -3 is newer and more complete.