I had a question regarding how MAME chooses the floppy format. I am using the apple3 emulation and trying to load a Prodos ordered disk image, but having issues. The disk is a modified atomic-defense disk but now in po format, so its not a prodos/sos disk as such.

Does MAME used the file extension or does it detect the sector ordering some other way? Is there a way to force using po ordering?