This happens on 15.11.2022, somebody mapped the 100’000th kilometer of nordic ski piste. .
These are the trails tagged piste:type=nordic. They describe several practices : backcountry touring, classic style on prepared rails or skating on large groomed pistes. In OSM, they are distinguished thanks to the key piste:grooming=backcountry/scooter/classic/skating or classic+skating.
Yves - Opensnowmap.org