GPX (the GPS Exchange Format) is a light-weight XML data format for the interchange of GPS data (waypoints, routes, and tracks) between applications and Web services on the Internet.

This schema defines the Garmin 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 below under Developer Resources.

This is not the latest version of GPXX. More recent versions are also available in the links below.

The Garmin Communicator Plugin supports transferring GPXX v2 to and from devices. Extensions are currently used to transfer Address information in a structured format for waypoints.
http://developer.garmin.com/schemas/gpxx/v3/">GPS Exchange Format Extensions XML v2