There are a few places where languages need to be specified, and it's quite complicated.

# Audio language

At the time of writing this is specified per content, in the content audio tab.  It is
used for writing:

- RFC5646SpokenLanguage metadata in sound MXF
- ISDCF name of DCP
- cover sheet

# Subtitle language

This is also specified per content, in the content subtitle tab.  It is used for writing:

- CPL MainSubtitleLanguageList (all languages present in the DCP)
- subtitle asset metadata
- ISDCF name of DCP
- cover sheet