MameData uses mainly the xml generated by MAME + history.dat + mameinfo.dat.
The lists of roms you make can be saved in .ini format compatible with Mame32.
You can also save the lists by defining the fields you want to use (RomName, GameName, Year, Category…) with the separator you like.
If you wish a special format for saving, just ask me for it by describing how it should be.