As to what version is it based on: MAME OS X version 0.111-1 is based on mainline version 0.111. The "-1" means it's the second MAME OS X version based on 0.111 (the first version is just 0.111). I've always used the mainline version as the first part of the MAME OS X version so that it's clear which version it's based off of. But this question keeps coming up, so apparently it's not that clear. Any suggestions on how to make this more clear are welcome.