Anatomy of a language code

The full language code (language tag) is consisted of four main parts:

Language (LANGCODE) is the only part of the language code (tag) that is consistently required. The other parts of the full language code are dependent on the requirements of the individual language and the environment. This part of the language tag uses the shortest version of the ISO 639 code and can include also macro languages (e.g., ‘NO’ for Norwegian languages).

Script is the four-letter identification of the written script, based on ISO 15924. This part of the language tag is optional and is used in case the language in a particular country/region can be written in more than one script.

Code of the country where the language is used. This optional part of the language tag is based on the ISO 3166 standards. Country code is used in case the language is used in more countries.

Code of a particular region within a country. This optional part is used only in cases when it is relevant and necessary to specify a particular region of a country.