Viewable waypoints are supported for any GPS using the D100, D103, or D104
waypoint formats. This includes the
GPS 12 and 12XL (version 3.01 and up), GPS 38, 40, 45, 45XL, 48, 55, 65, 75,
95, 120, 120XL, 125 Sounder, 126, 128, II, II+, and III.
For all other models, waypoints remain in their raw format. You can't edit them, but you can upload them back to the GPS.
GxPS supports the D201 Route Header type. This is used by all Garmin models except the GPS 55, 55 AVL, and StreetPilot. See the above section for route waypoint information.
All GPS models which store tracks are supported.
Please let me know. Adding support for other models isn't hard.