Group tag

[simoncn]

Group is a structural/containment tag like Album and Disc. Albums contain tracks, discs or groups; discs contain tracks or groups; groups contain tracks. Having two values in the Group tag for a track would mean the track belongs to two different groups, which is not possible (just as a track cannot belong to two different discs or two different albums). You would either need to use some other tag (such as Edition) to hold the additional metadata or combine work and edition information into a single GROUP value.