Language Codes
The value of the xml:lang
language attribute should be one of the two-letter
language codes defined in ISO-639, “Codes for the Representation of
Names of Languages,” found at http://lcweb.loc.gov/standards/iso639-2/langhome.html,
if such a code exists for the language in question.
For languages that aren’t listed in ISO-639, you can use a
language identifier registered with IANA; currently, about 20 of
these identifiers exist, including i-navajo, i-klingon, and i-lux. The complete list can be found at
ftp://ftp.isi.edu/in-notes/iana/assignments/languages.
All identifiers begin with i-.
For example:
<maxim xml:lang="i-klingon">Heghlu'meH QaQ jajvam</maxim>
If the language you need still isn’t present in these two
lists, you can create your own language tag, as long as it begins
with the prefix x- or X- to identify it as a user-defined
language code. For example, the title of this journal is written in
J. R. R. Tolkien’s fictional Quenya language:
<journal xml:lang="x-quenya">Tyalië Tyelelliéva</journal>