I noticed that Garmin City Navigator uses different thickness of linetype as you zoom out.

I can create 2 different TYP files (filename.txt) to be used with my mkgmap command and still use the same style files, but I do not know how to combine these different maps and how to specify at what zoom levels each map is to be visible.

Example:
Zoom level 0-2 (detailed map with wide roads 'detailed.img')

Zoom level 3-5 (overview map with thinner lines and some features removed 'overview.img)

How exactly to I combine these 2 maps into one 'combo' map. I know the file size will double

Do I use GmapTool?

Greg