Last spring, I made an OSM compatible file available to superimpose the GB National Grid on OSM maps using mkgmap. At that time I used Garmin codes 0x1c to 0x1e. These are normally used for administrative boundaries, but I was unable to find any sensible alternative codes. I have now found that it is possible to use high numbered codes which are not allocated, or are allocated to marine applications. I have successfully applied codes in the 0x10300 range: national_grid=100km [0x10302 level 3] national_grid=10km [0x10301 level 2] national_grid=1km [0x10300 level 1] These seem to work correctly in MapSource and on a GPS 60CSx. I have also made suitable TYP file entries, which are available on my download site http://www.rogercalvert.me.uk/OSM/grid, and are compatible with the TYP compiler in recent versions of mkgmap. Note that the compiled IMG file in the download package still uses the previous codes. Regards Roger -- ------------------------------------------------------------------------ Roger Calvert ------------------------------------------------------------------------