Songs not tracks

This is philosophically a little tricky, as I have learned from trying to create a Concert Tour schema with Dead tours as my model. When creating a set list for a show, there are obviously songs performed by the Dead that are from other artists. In this case it does seem to make more sense to have tracks as the expected type, since you do want that "recorded by" information, for example. It also makes sense in this case because it provides a way to link a song in the set list back to an album or live recording on which it appears. 

On the flip side, most of the best-known Dead songs are typed as "compositions" (song, btw, is a generally deprecated type from what I've recently learned), and if you want information such as who wrote it, that's where it comes from. I making set lists I wound up having a mix of "compositions" and tracks.

The thing that's very difficult to capture in our current model is the unreleased track (or movie, or what have you). The weirdness comes about because they are usually recorded, but haven't been released.

So, from my understanding, track is a good expected type if you want to tie into information about what album it's on, when it was recorded, etc. Composition is good if you want to tie into information about who was involved in its creation.  Most things we think of as songs are currently typed as tracks, because of the way in which we got the initial information from MusicBrainz. What I think we really need is a type that's a hybrid of the two, that can capture the composition information, but also peformance information as well (for example, there's currently no way to input which members of the band played what instruments on the track).