Programming and parent roms?

Hi just wondering what it means when you open a Rom folder and there's an extra bin file in there?
I'm looking to program so jpm impact roms... the program roms seem obvious. Sound appears to be labelled there's an extra bin file in there?
20059.bin (p1) 128k
20060.bin (p2) 128k
Cccsnd.bin (sound?) 512k

Extra?
1274.bin 512k
Thought you guys would be the ones to ask! Whats this extra file for can anyone help?
Thanks