Perhaps the holes were numbered. You know that at 70 and after Agent Orange cancer, a TIA that hospitalized me, to many times being under anesthesia and the knife I may get things wrong. I'm sure I saw the numbers.

Harry

I can assure you that there are no marking on the screws of Parker lock assemblies. Or on the lock plates themselves.

There are 4 screws and one threaded post. Of the 4 screws, on is a shorter length (for the sear spring). The other 3 are the same length. One of which is visible from the outside so it has a finished end. The other two are hidden behind the hammer and the ends are a rougher flat end.
Those are the only real methods of telling which screw goes where.

I stand corrected. Getting old is tough.

Harry