This format can...
This format has the following options: routevia .
TEF, internally called "TourExchangeFormat", is an XML based export format used by Map&Guide Motorrad-Routenplaner 2005/06™.
Because this is only an export format, GPSBabel does not support writing to this format.
GPSBabel also supports the bcr format, which may also be used with this program and supports both reading and writing.
gpsbabel -r -i tef,routevia -f in.xml -o gpx -F out.gpx