way/1443036863/history has via_ferrata_scale = B

What via_ferrata_scale = B means? It is not listed at via%20ferrata%20scale=*

way/878856321/history has so = BRG_MAPATHON _2020

What is the meaning of this unusual key? Is this tag needed?
Or maybe can it be expressed in a more typical way that would be easier to understand?
Or maybe this key can and should be documented as useful tagging schema?

way/942256506/history has so = b

What is the meaning of this unusual key? Is this tag needed?
Or maybe can it be expressed in a more typical way that would be easier to understand?
Or maybe this key can and should be documented as useful tagging schema?

way/763472881/history has so = bi

What is the meaning of this unusual key? Is this tag needed?
Or maybe can it be expressed in a more typical way that would be easier to understand?
Or maybe this key can and should be documented as useful tagging schema?

way/998224121/history has so = farmland

What is the meaning of this unusual key? Is this tag needed?
Or maybe can it be expressed in a more typical way that would be easier to understand?
Or maybe this key can and should be documented as useful tagging schema?

way/432327516/history has emergency = 36

What this tag means? Numeric value is unexpected here and it is unclear what it means

way/1385037910/history has tracktype = 4

Maybe it was supposed to be tracktype=grade4 ? See osm.wiki/Key%3Atracktype