Hi Mark
thanks
You said
You'll see plenty of examples if you look in the particles folder of your chosen template
Not realy, as I said, i search with notepad++ in my all tempate without find any exemple of file using these input above. Maybe i have to found them not in template but in side of gantry 5 component (dedicated to settings from the user in an admin panel ?). in that case as you said i don't need to learn about them (never touch core, first principe of joomla geek)
Yaml and twig file are easy to understand and improved if needed, thanks for Gantry 5
take care
Bertrand