Hi @linucks,
you can have a look into the source code: https://github.com/GIScience/openrouteservice-app/blob/master/app/constants/lists.js#L583-L618
once you know what each letter stands for, try experimenting a bit with the settings and you should be able to figure out, what values you need to use.
There is no official “documentation” for this as the purpose was to easily share route settings of routes you already created.
Please note that we currently work on a new client as well: openrouteservice.org/map
Ah, but i just realized that we decicded to ditch the key-value approach in favor of a data object.
So for your purpose you might find the classic client better suited.
Best regards