Artists proof
DEFINITION
A copy or reproduction that is outside the numbered copies of the limited edition but may be numbered with the prefix AP. By custom, the artist retains the APs for his/her personal use or sale and does not put an edition number on them. Sometimes artist's proofs are regarded as having more value, especially if they are the first prints pulled off non-lithographic plates before the plates were worn down. Source: Kimberley Reynolds, "Illustrated Dictionary of Art Terms"