ISO 639

ISO 639 is a set of standards by the International Organization for Standardization that is concerned with representation of names for language and language groups.

It was also the name of the original standard, approved in 1967 (as ISO 639/R) and withdrawn in 2002. The ISO 639 set consists of five parts.

Each part of the standard is maintained by a maintenance agency, which adds codes and changes the status of codes when needed. ISO 639-6 was withdrawn in 2014.

Scopes:

Types (for individual languages):

Bibliographic and terminology codes

The different parts of ISO 639 are designed to work together, in such a way that no code means one thing in one part and something else in another. However, not all languages are in all parts, and there is a variety of different ways that specific languages and other elements are treated in the different parts. This depends, for example, whether a language is listed in parts 1 or 2, whether it has separate B/T codes in part 2, or is classified as a macrolanguage in part 3, and so forth.

These various treatments are detailed in the following chart. The first four columns contain codes for a representative language that exemplifies a specific type of relation between the parts of ISO 639. The last column provides an explanation of the relationship, and the "#" column indicates the number of elements that have that type of relationship. For example, there are four elements that have a code in part 1, have a B/T code, and are classified as macrolanguages in part 3. One representative of these four elements is "Persian" [fas].

These differences are due to the following factors:

"Alpha-2" codes (for codes composed of 2 letters of the ISO 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 26² = 676), ISO 639-2 was developed using Alpha-3 codes (though the latter was formally published first).

"Alpha-3" codes (for codes composed of 3 letters of the ISO basic Latin alphabet) are used in ISO 639-2, ISO 639-3, and ISO 639-5. The number of languages and language groups that can be so represented is 26³ = 17,576.

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