ISO 639

ISO 639 is the set of international standards that lists short codes for languages. It was also the name of the original standard, approved in 1967 and withdrawn in 2002.

ISO 639 consists of different parts, of which four parts have been approved (parts 1, 2, 3 and 5). The other parts are works in progress.

The six parts of the standard

Standard	Name (Codes for the representation of names of languages -- ...)	First Edition	Current	No. In List
ISO 639-1	Part 1: Alpha-2 code	1967 (as ISO 639)	2002	185
ISO 639-2	Part 2: Alpha-3 code	1998	1998	>450
ISO 639-3	Part 3: Alpha-3 code for comprehensive coverage of languages	2007	2007	7704 + local range
ISO/DIS 639-4	Part 4: Implementation guidelines and general principles for language coding	(in DIS stage)	-	-
ISO 639-5	Part 5: Alpha-3 code for language families and groups	2008-05-15	2008-05-15	114
ISO/FDIS 639-6	Part 6: Alpha-4 representation for comprehensive coverage of language variation	(in FDIS stage)	-	?

Each part of the standard is maintained by a maintenance agency, which adds codes and changes the status of codes when needed.

Characteristics of individual codes

Scopes:

• Individual languages
• Macrolanguages (part 3)
• Collections of languages (part 1, 2, 5) (part 1 contains only 1 collection: bh; most collections are in part 2, and a few were added in part 5)
  • Group
  • Rest group
• Dialects
• Reserved for local use (part 2, 3)
• Special situations (part 2, 3)

Types (for individual languages):

• Living languages (part 2, 3) (all macrolanguages are living languages)
• Extinct languages (part 2, 3) (437, four in part 2 chb, chg, cop, sam; none in part 1)
• Ancient languages (part 1, 2, 3) (112, 19 are in part 2; and 5 of them, namely ave, chu, lat, pli and san, also have a code in part 1: ae, cu, la, pi, sa)
• Historic languages (part 2, 3) (63, 16 of them are in part 2, none has part 1 code)
• Constructed languages (part 2, 3) (19, 9 in part 2: epo, ina, ile, ido, vol, afh, jbo, tlh, zbl; five in part 1: eo, ia, ie, io, vo)

Bibliographic and terminology codes

• Bibliographic (part 2)
• Terminology (part 2)

Use of ISO 639 codes

The language codes defined in the several sections of ISO 639 are used for bibliographic purposes and, in computing and internet environments, as a key element of locale data. The codes also find use in various applications, such as Wikipedia URLs for its different language editions.

Code space

Alpha-2 code space

"Alpha-2" codes (for codes composed of 2 letters of the basic Latin alphabet) are used in ISO 639-1. When codes for a wider range of languages were desired, more than 2 letter combinations could cover (a maximum of $26^2=676$), ISO 639-2 was developed using Alpha-3 codes (though the latter was formally published first).Template:Fact

Alpha-3 code space

"Alpha-3" codes (for codes composed of 3 letters of the basic Latin alphabet) are used in ISO 639-2, ISO 639-3, and ISO 639-5. Mathematically, the upper limit for the number of languages and language collections that can be so represented is $26^3=17,576$.

The common use of Alpha-3 codes by three parts of ISO 639 requires some coordination within a larger system.

Part 2 defines four special codes mul, und, mis, zxx, a reserved range qaa-qtz (20 × 26 = 520 codes) and has 23 double entries (the B/T codes). This sums up to 520 + 23 + 4 = 547 codes that cannot be used in part 3 to represent languages or in part 5 to represent language families or groups. The remainder is 17,576 – 547 = 17,029.

There are somewhere around six or seven thousand languages on Earth today. So those 17,029 codes are adequate to assign a unique code to each language, although some languages may end up with arbitrary codes that sound nothing like traditional name(s) of that language.

Alpha-4 code space

"Alpha-4" codes (for codes composed of 4 letters of the basic Latin alphabet) is proposed to be used in ISO 639-6. The upper limit for the number of languages and dialects that can be represented is $26^4=456,976$.