@Sorin brought this up at last week’s working group meeting that there was some duplication of values/redundancy across the languages table. Particularly the lang column and some of the ISO 639 code columns.
the description for lang was updated. to specify that it is equal to the ISO 6396 code for that language. The iso6396 column was then deleted, also with the iso6393 column, as for almost all major languages the values in both standards were identical. Between iso6392B and iso6392T, iso6392B was deleted because it’s more for bibliographic purposes which are outside the scope of the ODM. iso6392T is for terminology, so it was maintained, along with the older iso6391 standard.
It seems that much of the updates from 6393 onward have been centred on dialects and linguistic grouping, which is more detailed than the ODM goes for language at this point and so the changes haven’t brought major changes for terms and codes that the ODM uses.