By topografix.
Example: “Shows multiple navigation track files this by a different track color”
Import in
Locus app. (Color & Navigate)
By Gps Visualiser: (Color)
https://www.gpsvisualizer.com/display/20220126031856-50217-map.html
Ediger_Eller to Cochem route A_B_C.gpx (90.5 KB)
(Garmin as usual is using an own extension for this task )
Extra by topografix. (Color + opacity + width)
https://www.gpsvisualizer.com/display/20220126050438-50217-map.html
Let’s not complicate things too much.
Colors contain the transparency (#AARRGGBB).
GPX 0.2 is deprecated, like the 1.0 with the “speed”.
We need a simple implementation like above.
If users need different % scale (there is no absolute width) for each track,
please create a new topic.
“Like above”
Validation error.
Validation check by Notepad ++ plugin.
As I am not a designer, my alternative method for a double check validation is:
Import in the very strict Garmin programs, for example (old) Mapsource.
The slightest problem and an import is rejected. Without any hint what’s wrong.
I’ve seen some OSMAND files to be rejected at imports into Garmin programs.
So best is (imo) to check for a correct gpx validation by the tools available
http://www.topografix.com/GPX/gpx_style/0/2/
Just checked. So it’s about gpx_style. I don’t see anywhere that this would be abandoned. And it is in use in some apps and web. Often limited to color only though.
line-styling
Extensions are extensions, it depends on readers to support them.
You decide Emux. There is indeed a lot of friendly software that is just tolerant of this. Garmin is not. Prevention is better than cure. So I think the following is still valuable. Validating GPX Files
Is there any official website that validates GPX extensions?
I do not use online validators.
I did have a quick look around, though.
No experience with it, but this one seems useful.
I use exclusively:
(Windows) https://notepad-plus-plus.org/
Notepad ++ with xml plugin is for me sufficiently useful with hints where things go wrong. A simple validation is a small effort, and gives you peace of mind that what you publish will not be considered corrupt too quickly, not even by the oh so strict Garmin programs. By the way, I am not a fan of very complex extensions, which are too error-sensitive.
You can see that Garmin imports are very strict in the following link.
https://t.ly/x9x4 (Use google translate)
Something like that really makes you go grey-haired, doesn’t it ?
Or is this a new puzzle sport then ? "Find the error(s).
Linux Notepad ++
Notepad ++ ?
Android Notepad ++
Not the same powerful product
Translated with www.DeepL.com/Translator (free version)
Validating GPX extensions is completely different from reading GPX extensions.
Any app can read such GPX files, if its parser can read them or skip extensions.
Properly validating custom xml files usually requires custom xml schemas.
Like the official GPX 1.1 schema or our custom map style schema.
Emux, Years ago I started with an Android app that exports next file.
Movetracker_2021-10-15_14-34-02_hearthrate_72_non_conform_gpx_1.1.gpx (40.7 KB)
The author told this was not a Garmin compatible file.
Open as text. Simple and super easy to understand, right?
I only changed the hearth rate 0 (no monitor) to 72 
I than expected gpx to always be that simple. False.
Comment by a gpx authority.
There are several extensions (fitness, temperature, etc.) that have proven themselves well and could be merged into our core without much hassle if we all followed the normal “ignore tags you don’t understand” guidelines in our readers. We still need a few contributors who are really behind this work to make it happen.
Well, I do not expect it to happen anymore. So we will have to get on with what is available, including all the inconveniences.
That’s right. 
