IANA language subtag registry data included in XLIFF Toolkit is out of date
Issue #37
new
XLIFF Toolkit validate if a given language value is a valid BCP47 language tag. To validate a subtag value, IANA language subtag registry data is used.
However, this data is not updated since 2014. If language subtag values are always validated, then the registry data file should be updated to the latest version.