[Tagging] `amenity=shelter` implies `building=yes`?

[Tobias Knerr]

On 18.06.2018 17:22, Kevin Kenny wrote:
> Would it be feasible to say that building=yes is a default (except,
> perhaps, for rock_shelter, sun_shelter) and that mappers are expected to
> place an expected building=no on the exceptions? 

Using building=no is a bad idea, as any object tagged building=* is
defined as representing a building – no matter the value. In particular,
data consumers should be able to fall back onto building=yes for all
unknown building values.