Conversation so far:
What was the Electric Light Orchestra's non-performing work?
For six years, Harvest and Epic/Legacy reissued Electric Light Orchestra's back catalogue. Included amongst the remastered album tracks were unreleased songs and outtakes.

Question: what albums or songs were in the back catalogue?
Self-contained rewrite: What albums or songs of Electric Light Orchestra's back catalogue were included amongst the remastered album tracks?