Relation to StandardsPrint
This 15th edition of the Ethnologue (2005) marked an important milestone in the development of the language identifiers, namely, their emergence as part of the draft international standard, ISO 639-3. (See History of the Ethnologue for a fuller discussion of the history of the language identifiers.) The aim of that standard is to enable the uniform identification of all known human languages in information systems. ISO 639-3 was devised to enable the uniform identification of all known languages in a wide range of applications, particularly including information systems. It provides as complete an enumeration of languages as possible, including living, extinct, ancient, and constructed languages, whether major or minor. The Ethnologue does not cover this entire scope; it seeks to catalog all known living languages, languages that have gone extinct since the inception of the Ethnologue around 1950, and languages that have no native speakers but which are still in use as a second language in certain communities. Long extinct and constructed languages that fall outside this scope are documented by Linguist List.
The most widely used standard for identifying languages in Internet documents (such as in HTTP headers or HTML metadata or in the XML lang attribute) is BCP 47 of the Internet Engineering Task Force. In that standard, any three-letter identifier from ISO 639-3 is recognized as a valid language identifier. Thus any of the three-letter codes reported in Ethnologue is valid for use in Internet documents.