I know I wrote that stuff somewhere, but I do not remember if it is here or on POI-Factory. As stated in my previous post you quoted, the 37xx suports only 256-color map symbol. I think Magenta is used for transparency and the map symbols can be 20x20 pixels max. Anything above will be cropped. As for the Where-To symbols, I suggest to use the 32-bit bitmap format. It works nicely and it supports the transparency correctly.