This format can...
read and write waypoints
This format has the following options: dbname .
QuoVadis for Palm OS marcosoft.com is a program for Palm/OS. Working with record definitions provided by MarcoSoft and further experimentation by Bruce Thompson and "Fuzzy" from the Geocaching Forums to nail down the format precisely.
Should work fine for import and export.
One thing of note, QuoVadis stores all waypoints in a single Palm Database without using categories. This means that it may be difficult to keep personal waypoints separate from generated waypoints. What Bruce recommends is taking the QuoVadisMarkerDB.PDB file synced down from your Palm Powered device and extract the waypoints you personally set to a GPX file. Then using GPSBabel's joining capabilities generate a new PDB file from the personal file and the other waypoint files of interest.
Currently the selection of icons to display and the scale at which to display them is hardcoded. Also there is no support for notes associated with waypoints. This will be addressed in a future revision.