Note: A specific string can identify different languoids in part 2 and part 3 or 5.
ISO 639 - Codes for the representation of names of languages
IdentifierTextLink
ISO 639-1:2002Part 1: Alpha-2 code
ISO 639-2:1998Part 2: Alpha-3 codeloc.gov/standards/iso639-2/
ISO 639-3:2007Part 3: Alpha-3 code for comprehensive coverage of languagessil.org/iso639-3/
ISO 639-4:2010Part 4: General principles of coding of the representation of names of languages and related entities, and application guidelines
ISO 639-5:2008Part 5: Alpha-3 code for language families and groups loc.gov/standards/iso639-5/
ISO 639-6:2009Part 6: Alpha-4 code for comprehensive coverage of language variants