 IETF language tag

An IETF BCP 47 language tag is a code to identify human languages.For example, the tag "en" stands for English; "es-419" for Latin American Spanish; "rm-sursilv" for Sursilvan; "gsw-u-sd-chzh" for Zürich German; "nan-Hant-TW" for Min Nan Chinese as spoken in Taiwan using traditional Han characters.