Lyman Mould Box Markings?

[Gtek]

Have looked and looked, here, there, everywhere, honest. I picked up a new old stock 457193C for a really good deal stamped Centennial Edition on mould. The box is white with black and gray striped sides. Quest- on the front of the box below Lyman mould blocks it has GROUP an A box, B box, C box and the A box is marked. Anybody? Heck a good believable tale would be great at this point so my OCD can move on to the next issue.

[Nueces]

Lyman grouped their moulds into price ranges, like RCBS dies, that's all. I have a bunch like that, even a few Bs or Cs.