Hi Hungerburg. I'm not sure I get what you're asking me. As far as I understand, the `climbing:grade:uiaa` and `uiaa_scale` keys represent the same information (a UIAA grade as described in https://www.theuiaa.org/grades-standards/rock-climbing/), just with two different names. Are you proposing that we use `uiaa_scale` for grades 1 and 2, and `climbing:grade:uiaa` for the higher grades? I think that may be rather confusing for mappers and map consumers alike.

The `climbing:grade:uiaa` naming is described in detail in the [Climbing#Grading](https://wiki.openstreetmap.org/wiki/Climbing#Grading) wiki page, as well as in [Key:sac_scale#See also](https://wiki.openstreetmap.org/wiki/Key:sac_scale#See_also), follows a consistent nomenclature regarding other difficulty scales mentioned in the [[Climbing]] page, and is used extensively (over 11 thousand uses at the time of writing) all over the world: https://taginfo.openstreetmap.org/keys/climbing%3Agrade%3Auiaa — many of which with values under 3.

In contrast, `uiaa_scale` had an order of magnitude fewer uses, and it was not described in the wiki except in the [highway=scramble proposal](https://wiki.openstreetmap.org/wiki/Proposal:Highway%3Dscramble#Tagging), and with the hard-to-enforce restriction for use in grades 1 and 2 only.

Is your objection only because of the `climbing:` prefix? I'm sympathetic to the desire for clear nomenclature, but then we'd lose consistency with the other hiking/climbing/mountaineering difficulty tags, and I doubt it would make a dent in the sensibleness of OSM keys anyway (I mean, don't we use the `highway` key for all sorts of roads, paths, etc.?)