"Greatest Hits" compilation, also referred to as "Rotten Apples".
Limited edition 2CD version contains a second disc of b-sides called "Judas O", a follow-up to Pisces Iscariot. The CD is designed to look like a CDR, possibly in reference to the online/trading communities.
"Real Love", "Lucky 13" and "Slow Dawn" are taken from Machina II, and are 3 of the 4 only tracks from Machina II that were officially released on CD (the other is "Try / Version 1" on the Untitled CD-Single). The "prev. unreleased" notes above are as written on the CD, and apparently actually mean "prev. unreleased on CD".