On this site we only use the 'GPX XML' format (to enter an trail trace or to download the GPS trace file) .
For traces from Cartoexploreur, you can use the 'Garmin PCX5' format , and rename your files with extension .trk ou .grm.
Files of formats 'GPX XML' and 'Garmin PCX5' are 'text' files, which means that you can open them with a word processor(for example Notepad on Windows).
If you have installed Google Earth on your computer, the file format used by Google Earth is 'Keyhole Markup Language'. Google Earth allows you to view in 3D your trail trace on a satellite picture of the area, to zoom in on the trace and to change the viewing position.