[Tagging] Template:KeyDescription - implies vs. requires

Tom Pfeifer t.pfeifer at computer.org
Thu Dec 31 14:46:45 UTC 2015

I just stumbled over the KeyDescription array in
which says:
     "  Implies amenity=social_facility "
while the tagging instructions and examples all say to explicitly
use amenity=social_facility + social_facility=*

This was on the page from the beginning, and has been copied
to a number of value pages for social_facility=* as well,
probably a simple mistake.

The definition of the 'implies' parameter on
is just referring to the same word:
"implies: a list of tags which are implied by this tag; see below for examples"

In my understanding, 'implies' would mean it does not have to be tagged explicitly,
such as motorway implies access by car, while here it means that the secondary key
social_facility=* would _require_ the primary tag "amenity=social_facility"

I'd like to do the following:
- refine the definition on the template page, e.g.
  "implies: a list of tags/values which are assumed when absent.
            See below for examples.
            Please explicitly tag properties when there are exceptions"

- on the social_facility pages, change the "implies: amenity=social_facility"
   into "combination: ..." (on top), since that is the closest from the
   available parameters.

Further, it might be useful to introduce the parameter "requires" or "required"
to the template, which is already proposed here:
with another example being "service=driveway" requires "highway=service".

What are the consequences of adding a parameter in the template?
Is there a process to consider?
Can a new parameter break existing evaluation software?


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