Well from http://www.loc.gov/standards/iso639-...glish_list.php
we're using the 639-1 code if it exists, and if not then the 639-2 code. So "ne" is "Nepali" (with "nep" the 639-2 code) and "new" is "Nepal Bhasa" and "Newari". Until someone actually using the code comments that a different code is needed, I think we'll leave it as is for now
Think of the Dublin Core as a challenge
You should have more time now as I think it will be frozen imminently for 0.6.0 and the next updates won't be seen until 0.6.1.