Passage: When the Lightweight Fighter program was announced in 1971, Northrop modified the P-530 into the P-600 design that would be designated YF-17A. Whereas the P-530 was intended as a multi-role aircraft, the P-600 was to be strictly an air-to-air demonstrator, and consequently the cannon moved from the underside of the fuselage, to the upper part. Design of the YF-17 and the prototype YJ101 engine (a development of the GE15 engine), consumed over a million man-hours, and 5,000 hours of wind tunnel testing.

Question: When Northrop changed the P-530 to the P-600, what was the new classification?
YF-17A