[Tagging] extend unsigned key to describe "no info on the ground" for a key

[marc marc]

Hello,

Le 13.06.19 à 15:15, Tobias Zwick a écrit :
> it semantically refers to the <...> key
it is a problem common to many keys but there is no overall coherence.

extend unsigned used for name with unsigned=<name of the key>
is easy to make a link betweeen the key and "no info on the ground".

it avoids:
- using funny no*=yes
- inconsistency (namespace <> underscore <> no <> ..) between usecase
- to be generalizable : any key can be filled in this way without having 
to discuss the value of the key and without having to code/learn
a "matching table".

Regards,
Marc