>>11954681
It makes perfect sense when you understand why they're named that way. A lot of times PCBS will have a chip name with the ROM # they are. So mame will name them just that.

For instance, Tower of Doom's USA pcb has the program roms named DAD, the number usually corresponds to the slot on the board (Slot 1, Slot 2 etc...)

So the roms will be DAD.01, DAD.02, the sprites and other data were mask roms with M as their extension so you'll see DAD12m, or DAD13m

It's down this way for preservation because if you own this board and that particular rom went bad, you know exactly which rom it is.