This refers to the values of the linked Discogs album, so this allows us to get the original Discogs values rather than the values stored in the song itself. This only has any effect if our song is linked to a Discogs release by having a URl Discogs Release and matching discno/trackno to a track on the linked release.
Artists
discogs_albumartist stores the album artist credit as single value with join phrases, discogs_albumartists return an array of the individual album artists making up the album artist credit.
discogs_artist stores the track artist credit as single value with join phrases, discogs_artists return an array of the individual artists making up the track artist credit.