Well it's the same for the typfile itself, meaning that in the typfile the definition you have to give is the same for getting it displayed. I'm not sure whether the data structure in the .img is the same too, but it could well be. In any case set 0x00 to 0x0000 otherwise the old definition files won't work. For example old: polyline|highway|motorway|0x01||10 should then be read as new and will be displayed without typfile: polyline|highway|motorway|0x01|0x00|10 polyline|highway|newtype|0x01|0x01|10, will however ONLY show up if you give it a definition in the .typfile. I suppose this could work. Garmin even uses a 5 digit definition like this in the typfile: [Polygon] Type=0x1101d Draworder=4 String=4,CONIFEROUS FOREST or [Polyline] Type=0x10e0c String=4,WATERFALL or [Polyline] Type=0x10f00 String=4,BANK So maybe for Polygons and Polylines their defintion would be accordingly polygon|natural|CONIFEROUS FOREST|0x11|0x01d|16 polyline|highway|WATERFALL|0x10|0xe0c|10 with even 3 digits in the subtype. Maybe also it doesn't matter how long the definition can be, the only important thing would be that it is accordingly attributed in the typfile. For POI both exists, for example: [POI] Type=0x6411 String=4,Tower or [POI] Type=0x11502 String=4,CAVE