Note: This page describes an obsolete version of GPSBabel that may substantially differ from the current or development version.
This format can...
read and write waypoints
read and write tracks
read and write routes
Garmin documents only PCX5, an older format limited to the lame NMEA six-character waypoint names that's treated as a second-class citizien in current versions of MapSource. In Mapsource, use file->import to read these files. If you name the files *.wpt, Mapsource will find them easier.
In general, you should prefer the "mapsource" file format to this one.