Help with rom names

[chuckaroo2000]

I was wondering where I might be able to figure out what the letters at the end of ROM files names mean.  I'm not talking about the file extentions, I know what those are.  Here is an example from a set of NES roms of what I mean:

RC Pro-Am (E) (PRG0) - what does the e and prg0 mean?
RC Pro-AM(PC10) - what does pc10 mean?
etc... sometimes the name is just followed by a U

Anyway there are different letters that proceed the rom name and I was just wondering if there is a way to figure it all out.  For every game there are like 5 - 10 different versions and I can't tell them apart.

Thanks

[Howard_Casto]

it's fairly self-explainatory....

(E) is the region code.... so that's the eurpoean release

(PRG0) means program rev 0..... that's some sort of revision name, not as important

(pc10) stands for playchoice 10.  So it's a hack of the playchoice arcade rom ready to run in you nes emulator. 

(U) is exteremely obvious it's stands for U.S. release man.