This format can...
read and write routes
This format has the following options: index .
Support for Navigon Mobile Navigator route (.rte) files. This is a very simple text format that only requires coordinates, but has fields for many other things. We only write coordinates as fields like 'city' and 'street' cannot typically be populated from other formats. www.navigon.com
Index of route to write (if more than one in source).
Because the format supports only one route, this option may be used on output to select a single route from a collection of routes read from a more expressive format. If you have, say, a gpx file that contains two routes, you may use this option to write them one at a time to individual files.
gpsbabel -i gpx -f routes.gpx -o nmn4,index=1 -F route1.rte -o nmn4,index=2 -F route2.rte