Difficulty levels in trail running

Trailrunning im Engadin bei Ramosch, Schweiz.
So that you can better classify the route suggestions, you will find below an overview of the difficulty levels easy, medium and difficult, which can serve as a non-binding orientation guide.
Difficulty For whom? Altitude difference & distance
Blue - easy
Beginner 100-500 eg / distance 5-10 km
Red - medium
Advanced 400-800 eg / distance 10-15 km
Black - hard
Advanced/Pro's 800+ eg / distance 15+ km
Difficulty Blue - easy Red - medium Black - hard
For whom?
Beginner Advanced Advanced/Pro's
Altitude difference & distance
100-500 eg / distance 5-10 km 400-800 eg / distance 10-15 km 800+ eg / distance 15+ km