Hi all, I have no idea how to solve the problem with crashes in MapSource when --route is used with --transparent and --dem . Maybe there is another flag that has to be changed, maybe it is not supported by Garmin. So, the best work around seems to be using transparent background polygons (0x4b) in combination with new option --transparent=semi and a TYP file that makes 0x4b transparent. Attached is a patch that implements new options like this, please suggest improvements for the documentation, else I'll use the same description for the doc as well. --transparent=full|semi Make the map transparent, so that if two maps covering the same area are loaded, you can see through this map to see details from the other map too. Typically used for maps containing just contour lines. See --draw-priority as well. Note that the combination of options --transparent and --route often cause problems in MapSource and Basecamp, e.g. routing may not work well or MapSource may crash when pressing the "Show profile..." button. If not given mkgmap writes background polygons (type 0x4b) and doesn't set transparent flag in the TRE header. If parameter full is used or no parameter is given mkgmap does not write the background polygons and sets the transparent flag. If parameter semi is used mkgmap writes background polygons and sets the transparent flag. A type file is needded that sets the 0x4b polygon to transparent. This allows good routing in MapSource and Basecamp but still may cause crashes in MapSource. Gerd