An undead object is an object that cannot be proven to be dead by the garbage collector, but whose liveness is dubious. For example, an ambiguous reference to an object on a page may mark the entire page as reachable. No further data is collected about that page. The other objects on the page will survive, even though their reachability has not been determined. They are undead.
Recorded live at the small jazz club, Klook's Kleek, in London, May 1968. This album set out to give listeners a real feel to what it was like to hear Ten Years After. Their eponymous first album was bluesy, but less emotional and passionate, and so the band decided to record the album live.