This schema defines the MTK extensions to be used with the GPX 1.1 schema.
The root elements defined by this schema are intended to be used as child
elements of the "extensions" elements in the GPX 1.1 schema. The GPX 1.1
schema is available at http://www.topografix.com/GPX/1/1/gpx.xsd.
This type contains data fields available in MTK waypoints that cannot
be represented in waypoints in GPX 1.1 instances.