This schema defines additional properties c:geo needs to store in a waypoint in a gpx file.
The root element is intended to be used in the appropriate extension point in the gpx waypoint type
(see http://www.topografix.com/GPX/1/0/gpx.xsd or http://www.topografix.com/GPX/1/1/gpx.xsd for details)
Currently two items are defined: visited and userdefined.