Step 1: Identify the context. "AP" is a standard notation used in limited edition printmaking, written on a print alongside the signature and sometimes the edition number.
Step 2: Define the term. The abbreviation "AP" stands for Artist's Proof. An Artist's Proof is one of a small group of prints set aside from the main edition for the artist's personal use. They are identical in quality to the main edition but are numbered separately (e.g., AP 1/5).