[DaveBlake]

In flac files these tags

BAND = "London Symphony Orchestra"
or
ENSEMBLE = "London Symphony Orchestra"
or
PERFORMER = "London Symphony Orchestra (Orchestra)"

will each result in a data entry of artist "London Symphony Orchestra" has role of "orchestra".
Only the PERFORMER tag has values with "artistname(role)" format.

Is there a simple document which lists all these mappings ?

Try this http://kodi.wiki/view/Music_tagging#Tags_Kodi_reads

Also this Picard documentation https://picard.musicbrainz.org/docs/mappings may help too .