Embarrassingly enough I have no idea what the the grids center-right and left do. I assume they somehow specify which screens are on which dmap?
DMap "mechanics" screen
the left one decides which screens on the map are to be used in the dmap for a cave, dungeon or bs-overworld type dmap, by way of moving the slider, and the right one is used to make the dungeon's map, the highlighted squares are the ones that show up when you get the map
Yeah, the slider on the left lets you put multiple 8x8 Dmaps on an 8x16 Map. Very space saving.😉
wow, that's a big picture!