[Tagging] 'Unknown' value.
19b350d2-b1b3-4edb-ad96-288ea1238eee at gmx.com
Mon Feb 5 20:08:10 UTC 2018
You have a point… :-)
The wiki already presents the idea that unknown means "unclear". 
Taginfo tells access=unknown has 20 thousand occurrences (i.e. 0.30% and ranking at the 11th position), which makes it not so unusual. 
The discussion here shows the value of "unknown" raises confusion, but admittedly if it was "unknown", "unclear", "uncertain", "difficult-to-tell" or whatever, it will always come down to awareness and getting used to the concept.
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