So just to be clear : by default if i don’t touch any settings or change any emulator, does batocera use mame2003 or mame2003plus ?
By default. the latest stable version of Batocera, Batocera V30, will use MAME 0.228. You can change that at advance system options or advanced game options to use MAME 0.78 or MAME 0.138, or even FBNEO, that is excellent for Neo Geo ROMs.
At the top it says that standard romset to use in “mame” directory is 0.78+ but later it seems that the standard romset to use is the 0.78.
Well, some roms that i am using, are .226 dumps and they are functioning without any problem.