ok, I've definitely chosen the wrong wording and it's not public domain (even if, since he started working on his emu, byuu himself defined Public Domain bsnes source for quite some time wink )

however, as byuu has stated many times, bsnes can be used freely as a base for implementation in other emu (and he already kindly donated to MESS part of the cart recognition code) and this kind of free reference implementation is what we need for MESS in this particular case wink