See http://tickets.musicbrainz.org/browse/STYLE-193 for the creation of the misleadingly-named "Soundtrack" work type

Currently I've used "song-cycle" to express the idea that this (Soundtrack work type) is
collection of smaller individual songs.
But as "reosarevok" pointed out this is "that's definitely not what
a song-cycle is".

"Soundtrack" work type was introduced because a container of works was desired.

It should be possible to use it:
1. As a placeholder. When no individual songs within movie are
named/specified then we just express that composer wrote music for
that movie.
2. As a container for individual songs that are part of that movie.
Between container and parts there will be "is part of" relationship.

I can't find any documentation on the Work types so it would be fantastic if "Soundtrack" was renamed to something that clearly indicates what it is. Right now, my ideas on that are "Soundtrack Group" or "Work Group".