I like @ezekielf definitions near the top of the thread (post #6), they are neat and really look ‘by the book’.
Sadly, the key ‘patrolled’ is very seldom used, and ‘operator’ nearly non-existent

piste_type='downhill' and grooming='backcountry' => patrolled=yes 102 out of 2862
piste_type='downhill' and grooming='backcountry' => operator=something 3 out of 2862

These are probably the tags I’d like to take into account to distinguish ‘official’ runs from ‘the secret stash’ :thinking:

At least one mapper as done piste_type=‘downhill’ and grooming=‘backcountry’ and informal=‘yes’.
We thanks them for their honesty :grinning: