DMap intricacies

[TheNewLink]

Anyone who's looked at the first quest knows that the dungeon DMaps are arranged in the way of a jigsaw puzzle, making the most of the space on each map. The sliding-bar thing (decides relative coordinates; to the left of the dungeon map fill-in area) necessarily overlaps that of other DMaps. You also know that some "secret" areas, despite not being on the map Link can pick up, are considered to be in the DMap.

I want an explanation. Since the user map isn't very reliable, considering secret rooms, and the editor seems to know it, how does ZQuest know which screen is part of which DMap?

[Freedom]

Zquest doesn't know.

The player, zelda-w.exe, knows because you warp from one dmap to the other, and the dmap is what sets all of the relative information.