GPX 1.0 was released in 2002 as a light-weight XML data format for the interchange of GPS data.
GPX 1.1 was released on 9 August 2004 and improved upon the existing GPX 1.0 standard. Notable changes were the introduction of <extensions> and a number of existing elements that were previously under <gpx> that were tweaked and moved into the <metadata> element.
Waypoints, routes and tracks were largely unchanged in GPX 1.1, aside from <url> elements being replaced by <link> elements and the introduction of <extensions>. However, <course> and <speed> were inadvertently dropped from the <trkpt> elements.
The majority of software that can import GPX 1.0 files can also import GPX 1.1 files since they are so similar. If <course> and <speed> are included in GPX 1.1 files they are typically recognised by software that already supports them in GPX 1.0 files.
Garmin have released a number of extension schemas for GPX 1.1 over the years, initially including “GpxExtensions” (see v2 and v3).
The GpxExtensions schema was subsequently split up into separate extensions, e.g. TrackPointExtension (see v1 and v2).
It is notable that TrackPointExtension v2 (circa 2015) introduced <speed>, <course> and <bearing>, providing a “proper” way to include course and speed in GPX 1.1 files.
Sadly, adoption of TrackPointExtension v2 for <course> and <speed> in GPX 1.1 files is not evident for the big brands (e.g. Garmin, Suunto, COROS) or within 3rd party apps for smartphones and smartwatches.
The TPX schema was created in July 2023, primarily for sports and activities that depend upon course, speed and accuracy estimates (see v1.0).
The extension schema includes <course>, <speed>, <roc> (rate of climb), plus various accuracy estimates for use within <trkpt> <extensions>.
It also includes additional <src> information for the hardware and software such as <manufacturer>, <product>, <serial>, <version>, etc.
One of the issues with the use of extensions for common elements such as <course> and <speed> is the lack of consistency:
<course> and <speed> in their GPX exports. This includes big brands and 3d party app developers.<course> and <speed> in the <trkpt> elements (not <extensions>) which is helpful, but it is not GPX 1.1 compliant.<extensions> but often refer to non-existent or undeclared schemas / namespaces - e.g. <gpxdata:speed><course> and <speed> in GPX 1.1 files.I wrote about the GPX format and provided further details about speed in GPX files earlier in 2023, whilst investigating GPX compatibility issues affecting the speedsurfing community.