TS ISO 639

TS ISO 639 is the standard for codes used to identify individual languages and language groups, together with the terminology and naming principles that support those codes. It provides a common framework for language identifiers and reference names, helping systems represent the same language consistently across catalogs, databases, multilingual content workflows, and information exchange.

How language identifiers are organised

The document sets out rules for the selection, formation, presentation, and use of language identifiers, as well as for language reference names. In general technical use, such coding schemes replace long or variable language names with short, controlled identifiers, which makes language data easier to store, search, exchange, and process in bibliographic, documentary, and digital systems.

It also gives principles and guidelines for the selection, formation, and presentation of language names in English and French, and provides provisions for adopting standardised language code elements using names in languages other than English or French. The standard notes that the ISO 639 language code is maintained by the ISO 639 Maintenance Agency and offers guidance on combining language identifiers with identifiers from other code systems.

What is outside the scope

• Reconstructed languages
• Formal languages
• Computer programming languages
• Markup languages

This boundary is important because ISO 639 is intended for natural human languages and language groups, not for technical or artificial languages. In practical terms, it supports consistent language metadata in cataloguing, archiving, publishing, translation systems, and software that needs to distinguish human language from formal notation or code. The result is clearer interoperability and more reliable language representation across systems.