[mkgmap-dev] splitter, mapid

One thing I think I missed, is that each tile on a garmin device needs a unique mapid.   A different family-id and mapname for each gmap is not sufficient.   Does this sound correct? I'd been downloading US states from Geofabrik, creating maps with unique family-id, mapname, every name & id that seemed important, (with mkgmap)  but when I put them on the Garmin they all wouldn't show up.    Only when I went back to the splitter step & used a different mapid did they all show up. Sometimes I'm not too good at reading directions,  did I overlook this someplace? Brad