language code definition 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.