One of the problems you first face when customising your own maps is trying to understand what the default Garmin types correspond to (lines, polygons and POIs). I've written a small application in c that will output a regular grid of POIs, polygons or lines and have used that to develop the following screenshots and IMG files so that you can see what the Garmin defaults look like.
The screenshots are taken from MapSource 6.15.7 and so will differ from what you get if:
To overcome the latter, download the linked IMG files and install them into your GPS to see what will actually get displayed.
- You use a different version of MapSource
- You look at what appears on your GPS
0x0001 to 0x0064
0x1601 to 0x1664
The following screenshot shows all the polygons that MapSource can display.
Download the IMG file, rename it to gmapsupp.img and copy it to your GPS to see how these actually display. Note that the IMG file contains definitions for 100 polygons (i.e. up to 0x64), but most of them above 0x53 won't display.