My third wish

[simoncn]

The main reason "box set" hasn't been implemented yet has been the lack of any clear standard or obviously intuitive way to add an extra level to the containment hierarchy. My proposal builds on the current approach for albums/discs and tracks/groups, so it should (hopefully) be fairly straightforward to implement and also easy to explain to users. As far as I know, the AlbumGroup and AlbumNumber tags are not currently used for any other purpose. Perhaps AlbumGroupNumber or AlbumGroupIndex would be better than AlbumNumber, as AlbumNumber could mean something else. I am currently leaning towards AlbumGroupIndex but might have changed my preference by tomorrow

I would expect album groups to be incorporated into the current artwork search hierarchy for album/disc/group/track. I think this proposal meets all the "box set" requirements that have been discussed on the forum.