This format can...
read and write waypoints
read and write tracks
read and write routes
This format has the following options: index .
This format supports the Suunto Trek Manager (STM) WaypointPlus format. This is a simple format with coordinates and a time stamp. Route points also have a short name. A single file may only contain one route or one track.
Index of route/track to write (if more than one in source).
Because the format supports only one route or track, this option may be used on output to select a single route or track from a collection of routes and tracks read from a more expressive format. If you have, say, a gpx file that contains three routes, you may use this option to write them one at a time to individual files.
gpsbabel -i gpx -f routes.gpx -o stmwpp,index=1 -F route1.txt -o stmwpp,index=2 -F route2.txt -o stmwpp,index=3 -F route3.txt