DCNC - Appendix #1ab - Language Codes
The language codes are based on ISO 639-1, 639-2, or 639-3 codes*. When a 2 digit 639-1 code is available, this is the preferred code. Codes beginning with “Q” are not represented in the ISO Standard, but are named using the 639-2 methodology for additional languages. “LAS”, representing Latin American Spanish, is a special case in that LAS represents Lama (spoken in Togo) in the 639-3 codes. Due to the widespread use of “LAS” as Latin American Spanish in Film Distribution, however, we have chosen to keep it as Latin American Spanish for purposes of this convention. If you have an older DCP with a language code that isn’t listed in the table below, it may be an out-of-date code. A list of out-of-date codes can be found in Appendix 1c.
Language codes are complex. Please review http://isdcf.com/papers/ISDCF-Doc7-DigitalCinemaLanguageCodes.pdf for more information including the use of RFC-4647 and IANA Subtag Registry for codes and sub-codes.