The patch fixes the following tagging: polygon A: leisure=nature_reserve (the complete area) polygon B: natural=water (only the inner area) multipolygon relation: natural=wood and outer=polygon A and inner=polygon B (only the surrounding area) => See also thread http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2010q3/009112.html The patch fixes also problems with cascaded multipolygons. MP1: outer P1 [natural=wood] inner P2 [natural=water] MP2: outer P2 [natural=water] inner P3 [natural=sand] Without this patch P2 was added twice to the map. Once with the complete polygon area and once with the cut out P3. I think this patch will also make it possible to remove the unlovely tag-removal-map used by the multipolygons. But first I have to check that in deep. Please test this patch carefully with some of your well known multipolygons! I would not be surprised by the patch containing some unwanted stuff... WanMil