This part of ISO 639 provides a code, published by the Registration Authority of ISO 639-3, consisting
of language code elements comprising three-letter language identifiers for the representation of
languages. The language identifiers according to this part of ISO 639 were devised for use in a wide
range of applications, especially in computer systems, where there is potential need to support a large
number of the languages that are known to have ever existed. Whereas ISO 639-1 and ISO 639-2 are
intended to focus on the major languages of the world that are most frequently represented in the total
body of the world's literature, this part of ISO 639 attempts to provide as complete an enumeration of
languages as possible, including living, extinct, ancient and constructed languages, whether major or
minor, written or unwritten. As a result, this part of ISO 639 deals with a very large number of lesserknown languages. Languages designed exclusively for machine use, such as computer-programming
languages and reconstructed languages, are not included in this code.
Knowledge of the world's languages at any given time is never complete or perfect. Additional language
identifiers may be created for this list when it becomes apparent that there is a linguistic variety that
is deemed to be distinct from other languages in accordance with the definitions in Clause 3 and their
elaboration in Clause 4. In addition, the denotation of existing identifiers may be revised or identifiers
may become deprecated when it becomes apparent that they do not accurately reflect actual language
distinctions. In all such changes, careful consideration is given to minimize adverse effects on existing
implementations.