ISO 639-3:2007, Codes for the representation of names of languages – Part 3: Alpha-3 code for comprehensive coverage of languages, is an international standard for language codes in the ISO 639 series. It defines three-letter codes for identifying languages. The standard was published by International Organization for Standardization (ISO) on 1 February 2007.
ISO 639-3 extends the ISO 639-2 alpha-3 codes with an aim to cover all known natural languages. The extended language coverage was based primarily on the language codes used in the Ethnologue (volumes 10–14) published by SIL International, which is now the registration authority for ISO 639-3. It provides an enumeration of languages as complete as possible, including living and extinct, ancient and constructed, major and minor, written and unwritten. However, it does not include reconstructed languages such as Proto-Indo-European.
ISO 639-3 is intended for use as metadata codes in a wide range of applications. It is widely used in computer and information systems, such as the Internet, in which many languages need to be supported. In archives and other information storage, it is used in cataloging systems, indicating what language a resource is in or about. The codes are also frequently used in the linguistic literature and elsewhere to compensate for the fact that language names may be obscure or ambiguous.
Language codes
ISO 639-3 includes all languages in ISO 639-1 and all individual languages in ISO 639-2. ISO 639-1 and ISO 639-2 focused on major languages, most frequently represented in the total body of the world's literature. Since ISO 639-2 also includes language collections and Part 3 does not, ISO 639-3 is not a superset of ISO 639-2. Where B and T codes exist in ISO 639-2, ISO 639-3 uses the T-codes.
, the standard contains 7,916 entries. The inventory of languages is based on a number of sources including: the individual languages contained in 639–2, modern languages from the Ethnologue, historic varieties, ancient languages and artificial languages from the Linguist List, as well as languages recommended within the annual public commenting period.
Machine-readable data files are provided by the registration authority. Mappings from ISO 639-1 or ISO 639–2 to ISO 639-3 can be done using these data files.
ISO 639-3 is intended to assume distinctions based on criteria that are not entirely objective. It is not intended to document or provide identifiers for dialects or other sub-language variations. Nevertheless, judgments regarding distinctions between languages may be subjective, particularly in the case of language varieties without established literary traditions, usage in education or media, or other factors that contribute to language conventionalization. Therefore, the standard should not be regarded as an authoritative statement of what distinct languages exist in the world (about which there may be substantial disagreement in some cases), but rather simply one useful way for identifying different language varieties precisely.
Code space
Since the code is three-letter alphabetic, one upper bound for the number of languages that can be represented is 26 × 26 × 26 = 17,576. Since ISO 639-2 defines special codes (4), a reserved range (520) and B-only codes (22), 546 codes cannot be used in part 3. Therefore, a stricter upper bound is 17,576 − 546 = 17,030.
The upper bound gets even stricter if one subtracts the language collections defined in 639-2 and the ones yet to be defined in ISO 639-5.
Macrolanguages
There are 58 languages in ISO 639-2 which are considered, for the purposes of the standard, to be "macrolanguages" in ISO 639-3.
Some of these macrolanguages had no individual language as defined by ISO 639–3 in the code set of ISO 639-2, e.g. 'ara' (Generic Arabic). Others like 'nor' (Norwegian) had their two individual parts ('nno' (Nynorsk), 'nob' (Bokmål)) already in ISO 639-2.
That means some languages (e.g. 'arb', Standard Arabic) that were considered by ISO 639–2 to be dialects of one language ('ara') are now in ISO 639–3 in certain contexts considered to be individual languages themselves.
This is an attempt to deal with varieties that may be linguistically distinct from each other, but are treated by their speakers as two forms of the same language, e.g. in cases of diglossia.
For example: ara | ISO 639-3 (Generic Arabic, 639–2) arb | ISO 639-3 (Standard Arabic, 639–3)
See for the complete list.