The release group style guideline notably lacks a primary type section although it does clarify on secondary types.

For example, the waterfall release strategy commonly used for digital media can be confusing to those not familiar with it or due to the absence of a formal guideline

Existing discussions for waterfall release strategy:

• https://musicbrainz.org/edit/104680003
• https://musicbrainz.org/edit/104988975
• https://musicbrainz.org/edit/108441635
• https://musicbrainz.org/edit/117989803
• https://musicbrainz.org/edit/122898025
• https://musicbrainz.org/edit/133849308
• https://musicbrainz.org/edit/134244746

See also recently added definition requiring transclusion: https://wiki.musicbrainz.org/Release_Group%2FType?diff=78782&oldid=76807