A language is listed ashistoricwhen it is considered to be distinct from any modern languages that are descended from it; for instance, Old English and Middle English. Here, too, the criterion is that the language have a literature that is treated distinctly by the scholarly community.
A language is listed aslivingwhen there are people still living who learned it as a first language. This part of ISO 639 also includes identifiers for languages that are no longer living.
This part of ISO 639 also includes identifiers that denoteconstructed(or artificial) languages. In order to qualify for inclusion the language must have a literature and it must be designed for the purpose of human communication. It must be a complete language, and be in use for human communication by some community long enough to be passed to a second generation of users. Specifically excluded are reconstructed languages and computer programming languages.
A language is listed asancientif it went extinct in ancient times (e.g. more than a millennium ago). Identifiers are assigned to ancient languages which have a distinct literature and are treated distinctly by the scholarly community. It would be ideal to be able to assign identifiers to ancient languages on the basis of intelligibility, but ancient records rarely contain enough information to make this possible. In order to qualify for inclusion in ISO 639-3, the language must have an attested literature or be well-documented as a language known to have been spoken by some particular community at some point in history; it may not be a reconstructed language inferred from historical-comparative analysis.
A language is listed asextinctif it has gone extinct in recent times. (e.g. in the last few centuries). The criteria for identifying distinct languages in these case are based on intelligibility (as defined for individual languages).
In the code table for ISO 639-3, theindividual languagesare identified as being of one of the following five types.