I can't find anything comparable in the WIS, but there is a bit in the Haynes manual. And, as to be expected, it doesn't always match!
Haynes says that there are five sizes of piston AB, A, C 1 & 2. With 1 & 2 being the oversize ones. The size is stamped into the top of the piston and also on the front top corners of the engine block. It then goes on to say that if the clearance of the piston in the bore is more than the nominal new max size, "the opinion of an engine reconditioner" should be sought as to whether a rebore is required.
So nothing definite...