Hi WanMil and others, Some time ago, there was discussion that the MultiPolygon code in mkgmap should tag the lines that it generates when splitting multipolygons to polygons. I think that there is a genuine need to split large multipolygons to smaller multipolygons in the OSM data too. For example, I generated multipolygons for the lake Saimaa in the past couple of weeks. I split it to maybe 10 or 20 multipolygons, some of them still huge (hundreds of ways in the relation, many of them consisting of 500 nodes). A fellow mapper who generated the natural=coastline for many Finnish waters in the first place got upset of the artificial splitting. I suggested a solution where the artificial split lines would not be given any natural=water or natural=coastline tag, but something else, say, artificial=yes. What do you think? Is there an existing tag that we could use for this? Is there now a multipolygon around the Canarian Islands? I could not find one. I am considering defining some multipolygons with some artificial cut lines on the Finnish coast, so that I would get water without --generate-sea and could work around the limitations of the Geofabrik map extracts by defining the borders of the sea multipolygons within the Geofabrik cutting boundary. Marko