Data Types
In GPX, a collection of points, with no sequential relationship (the county towns of England, say, or all Skyscrapers in New York), is deemed a collection of individual waypoints. An ordered collection of points may be expressed as a track or a route. Conceptually, tracks are a record of where a person has been, routes are suggestions about where they might go in the future. For example, each point in a track may have a timestamp (because someone is recording where and when they were there), but the points in a route are unlikely to have timestamps, because the author is suggesting a route which nobody might ever have traveled.
The minimum properties for a GPX file are latitude and longitude for every single waypoint. All other elements are optional. Some vendors, such as Humminbird and Garmin, use extensions to the GPX format for recording depth of water and other parameters.
Read more about this topic: GPS EXchange Format
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