Language tags are a formalism, described in RFC 1766, for declaring
what language form (language and possibly dialect) a given chunk of
information is in.

This library provides functions for common tasks involving language
tags (notably the extraction of them, comparing them, and testing the
formal validity of them) as is needed in a variety of protocols and
applications.

WWW: http://search.cpan.org/dist/I18N-LangTags/