I am wondering if the GameEx MAP files have the ability to send different command lines to a given emulator (in this case MESS) for any given rom file. For example, I have one list for all Genesis/Megadrive games, however MESS can not distinguish and automatically select the appropriate clone in order to run some of the Megadrive games, if using Genesis as system in the MESS command line (and the GameEx ini) I will get an error saying that the rom is not playable on the genesis. Before GameEx, I had been using MAMEWah and it had allowed for separate ini's to be created for each rom, so that I only had one Genesis/Megadrive list but was able (albeit after a little work)to run any rom by changing the command line on the fly. It appears that the Map files allow custom naming, but can custom command lines also be sent along. Or am I stuck creating a separate MegaDrive emulator. Thanks.