Internet RFC 3066 'Tags for the Identification of Languages' specifies a primary
subtag which is a two-letter code taken from ISO 639 part 1 or a three-letter
code taken from ISO 639 part 2, followed optionally by a two-letter country
code taken from ISO 3166.
Internet RFC 1766 'Tags for the identification of Language' specifies a two
letter code taken from ISO 639, followed optionally by a two letter country
code taken from ISO 3166.
Internet RFC 3066 'Tags for the Identification of Languages' specifies a primary
subtag which is a two-letter code taken from ISO 639 part 1 or a three-letter
code taken from ISO 639 part 2, followed optionally by a two-letter country
code taken from ISO 3166. When a language in ISO 639 has both a two-letter
and three-letter code, use the two-letter code; when it has only a three-letter
code, use the three-letter code. This RFC replaces RFC 1766.
A general statement describing the education or training context. Alternatively,
a more specific statement of the location of the audience in terms of its
progression through an education or training context.
The described resource is a version, edition, or adaptation of the referenced
resource. Changes in version imply substantive changes in content rather than
differences in format.