REQUIRED FIELD

The Language Code is another required field for adding or modifying languages. The language code contains a list of matching laguage identifiers that will be used in automatic browser language identification. You can specify multiple language codes for any given language, separating them by commas or semicolons. You will want the language codes you enter here to match those that are generally sent by web browsers. For example, the language code for English is en, while "en-US" and "en-GB" are common localizations. Including 'en' will catch both of those localizations as well.

To see a list of all of the language codes, you can visit Wikipedia: List of ISO 639-1 codes.