[mkgmap-dev] type file and resolutions

Hi, does anyone know whether it is possible to use different type files for different resolutions, or to restrict the resolution range of the type file. The problem I am having is that in my map I only use resolutions 24,22,20,18 and 16. Below that I allow the base map to take over. However, in BaseCamp I am getting the base map displayed using my type file (and the whole world uses it, not just the area of my map). If I try the same thing with a commercial map, I can see the base map take over seamlessly at low resolutions. Any suggestions? Thanks, Mike