You can use MapSource to open your GPX file with waypoints and do some editing so you can categorize them as you wish. First open MapSource open "Edit" tab - "Preferences" - "Waypoints Categories" and name the categories as you wish. Now do a right click to the waypoint you want, go to "Waypoint Properties" and select the category/ies you wish. You can edit more than one waypoint at a time. Now you ready to send the waypoints from MapSource to your device, you 'll find them categorized.