1991 Topps

[steve B]

Originally Posted by Zach Wheat

Arthur,

When they make corrections to the "A" sheet, they put an "*" at the bottom of the card on the reverse by the copyright logo. I am not sure how the A*B* comes about but I suspect the card was originally on the "A" sheet and then moved to the "B" sheet along with other changes.....just guessing on that though.

So the latest corrections should all be on a sheet with a "*" on it.

I've heard that before, but only fairly recently.
The cards are printed on a double size sheet, 264 cards. A and B, C and D, E and F.
Usually there's only one sheet indicator, and it very nearly always has the asterix. I can't recall seeing one without it in decades.
If you notice, the A is always spaced out from the copyright when it's by itself. That's most likely from them using a pasteup that included both sheet letters, either on the original art, or on the mask. Then the one that wasn't needed was blocked out. Except for some reason in 1991 they missed it on a lot of cards.
(There are exceptions, like the year they offered a few cards for a small payment and some wrappers to help people finish sets. There was enough demand for stars that they made a special sheet)