[mkgmap-dev] Motorway exits and the base map

Whilst looking at motorway exits on my Legend recently, I noticed that in "Find/Exits" the context menu lets you choose which map to use for exits (unlike all other searches). By default, "choose best maps" is selected; I don't know how it makes this choice - perhaps the map has some sort of resolution/accuracy field somewhere, and ours isn't marked as being more accurate than the base map? I know it's a bit late to add to this old discussion, but perhaps it might help.