I discovered that the latitude value in the boundary nodes (NOD3) table should have 180 degrees added to it (aka 0x800000) to make it consistent with Garmin maps. The fact that we can route between (our) tiles without this mod shows that it doesn't really matter but we may as well be as authentic as possible. So, tiddly patch attached, please test it with regard to inter-tile routing. I am not expecting anything to change. Cheers, Mark