These are songs that are not on any album in their original form.
This includes b-sides, unreleased tracks, compilation tracks, and christmas singles.
I classify b-sides as any non-album track. What I'm counting as an album is the original release of the album, not any re-releases containing bonus tracks. Compilation tracks are songs that appear on compilations. They also do not appear on any (standard) album (not counting "best of" compilations). Unreleased tracks are songs which have not appeared on any album (meaning they did not appear on the original release of the album). They may be studio outtakes, or unreleased live tracks.
Unreleased Songs and Studio Outtakes
Out of Time Outtakes:
All of the B-sides/Compilation Tracks
All of the Christmas Tracks
All of the Outtakes