ISO 639 macrolanguage

A macrolanguage is a group of mutually intelligible speech varieties, or dialect continuum, that have no traditional name in common, and which may be considered distinct languages by their speakers. Macrolanguages are used as a book-keeping mechanism for the ISO 639 international standard of language codes. Macrolanguages are established to assist mapping between different sets of ISO language codes. Specifically, there may be a many-to-one correspondence between ISO 639-3, intended to identify all the thousands of languages of the world, and either of two other sets, ISO 639-1, established to identify languages in computer systems, and ISO 639-2, which encodes a few hundred languages for library cataloguing and bibliographic purposes. When such many-to-one ISO 639-2 codes are included in an ISO 639-3 context, they are called "macrolanguages" to distinguish them from the corresponding individual languages of ISO 639-3. According to the ISO, Some existing code elements in ISO 639-2, and the corresponding code elements in ISO 639-1, are designated in those parts of ISO 639 as individual language code elements, yet are in a one-to-many relationship with individual language code elements in [ISO 639-3]. For purposes of [ISO 639-3], they are considered to be macrolanguage code elements. ISO 639-3 is curated by SIL International; ISO 639-2 is curated by the Library of Congress (USA). The mapping often has the implication that it covers borderline cases where two language varieties may be considered strongly divergent dialects of the same language or very closely related languages (dialect continua); it may also encompass situations when there are language varieties that are considered to be varieties of the same language on the grounds of ethnic, cultural, and political considerations, rather than linguistic reasons. However, this is not its primary function and the classification is not evenly applied. For example, Chinese is a macrolanguage encompassing...