ISO 639-2, the international standard for language codes, assigns the code chu to Church Slavic; Old Slavonic; Church Slavonic; Old Bulgarian; Old Church Slavonic.
- ISO 639-2/B code: chu
- ISO 639-1 code: cu
- English name: Church Slavic; Old Slavonic; Church Slavonic; Old Bulgarian; Old Church Slavonic
- French name: slavon d'église; vieux slave; slavon liturgique; vieux bulgare