Mold Number

[Lonestar22]

I was given a Lyman mold with the following number, 452460a. I understand the numeric identification, but what does the letter "a" identify?
Thanks for your time.

[Gar]

It's my understanding (through hearsay) that the letter refers to the cherry that the factory used to cut the mold, A being the first cutter, B the second, etc.
Again, no personal knowledge only hearsay.