Specifies the URL or the file name of the icon image for the icon.
If you want to use an image from a local file system, you can specify the file name either as relative path:
icon-image : icons/SJJB/png/transport_parking.n.32.png
in which case Maperitive will use its installation directory as the base directory to look for the image file, or as an absolute path:
icon-image : d:\somewhere\icons\SJJB\png\transport_parking.n.32.png
You can also use an image from the Web:
icon-image : http://somewhere.com/icons/myicon.png