ISO 639-6, Codes for the representation of names of languages — Part 6: Alpha-4 code for comprehensive coverage of language variants, is an international standard in the ISO 639 series, developed by ISO/TC 37/SC 2 (International Organization for Standardization, Technical Committee 37, Subcommittee 2: Terminographical and lexicographical working methods). It contains four-letter codes that denote variants of languages. This allows to differentiate between, for example, historical (glvx
) versus revived (rvmx
) Manx, while ISO 639-3 only includes glv
for Manx.
The data supporting ISO 639-6 is being researched and compiled by GeoLang on behalf of the British Standards Institution (BSI). ISO 693-6 was published in 2009.