I've had a couple of 65s for a few years, but just recently noticed one has
SD-01A "Personal Investment" and the other has SD-01B "Day of the Week" as
the first mag card in their respective Standard Pacs.

I had thought the "A" "B" "C", etc. suffixes represented rewrites for bug
fixes to the software. But at least in this instance, it's a completely
different program.