]> The content of the lang attribute is a hyphen-separated list of case-insensitive tokens where the first token, if one character, is "i" or "x"; if two characters, is an ISO 639-1 language code; if three characters, is an ISO 639-2 language code. The second token, if two characters, is an ISO 3166-1 country code; if from three to eight characters, is an IANA-registered language code. The meaning of other tokens is undefined. This documentation briefly summarizes RFC3066, which obseletes RFC1766. Examples: en-GB ja-JP no-bok sgn-US i-navajo cel-gaulish XML specification, Language Identification (in the second edition as modified by errattum E11) RFC 3066 Registration authority for ISO 639-1 and -2 Registration authority for ISO 3166 IANA-registered language codes