language code
ISO 639-1
ISO 639-2
<human language, standard> A set of standard names and
abbreviations maintained by {ISO} for identifying human
languages, natural and invented, past and present. Each
language has a list of English and French names and an ISO
639-2 three-letter code. Some also have an ISO 639-1
two-letter code.
The list even includes the Klingon language from the Star Trek
science fiction series.
Latest list
(http://www.loc.gov/standards/iso639-2/php/English_list.php).
There are also {country codes}.
(2006-12-11)