Topographic seems to be source for this common file format used by many geographic information system devices and applications. The current version has been around since 9 August 2004.
The GPX file format is a lightweight XML data format. This means it is a text file with special tags to identify a known set of fields common to GIS systems like latitude, longitude, elevation, description, and name. An example can be seen at Garmin Mass Storage Mode Devices which describes how Garmin uses the format for its GPS devices. GPSBabel describes some of the other extensions for the format.
This is the most capable and expressive of all the file formats supplied. It is described at topografix.com and is supported by EasyGPS, ExpertGPS, and many other programs described at topografix.com
GPSBabel’s reader of this module attempts to preserve tags it doesn’t really understand.
Garmin has a page that describes several of the GIS oriented file formats they support at Garmin Formats. These include AXM, Device XML, GPX, GPXX, KML, and TCX with links to the various schema definitions.
A nice history of the file format is at Travel By GPS The History of eXchanging GPs Data.
The backup is to use CSV files. These are also text but do not have explicit fields and are flat files whose data needs some interpretation. Each line is an individual record. A GPX file has defined fields made explicit and each field is of a know type. A GPX data record may be more complex than CSV formats would support.
The key issues at present is how to fill a GPX record from CSV sources and then see how the fields in the source data end up on the target device. Once that is figured out, it would be possible to figure out how to parse and clean the data source for desired results in the GPS device.
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