041 Subfield $e - Language code of librettos:

For music, subfield $e contains the language code(s) of the printed text when the item contains the vocal/textual content of the work(s) printed as text -- whether as accompanying material or printed with the item. Note: Despite its name, this subfield is not restricted to librettos. However, it is not used for items covered by subfield $g .

Example:

008/35-37 fre

041 0#$afre$efregerita