Ah. So at least - and please correct me if I'm wrong here (which I am bound to be) - but at least *some* of the machines/drivers were selected because they, either historically or currently, were 'pain-points' for MAME, some way or the other. And then some more drivers because they represented 'popular' machines/hardware. And then, not to make the 'reproducibility factor' too large, not too many machines in total.