[Tagging] Feature Proposal - RFC - protection_class=* (Words, not numeric codes)

[Joseph Eisenberg]

> one tag is supported for displaying "one kind of thing"

That's not at all the same as "One feature, one OSM element".

The basic principle is that you don't create 2 different database
objects for the same thing: you don't map a single school as a node
and as an area (closed way) around the node.

Similarly, it's a good idea to add only one main feature tag to a
database object.

While some mappers like to save time by adding barrier=hedge to an
amenity=school closed way, this makes it ambiguous: is the hedge an
area or a line? If there is a name, is it the name of the hedge or the
name of the school? A human can easily pick the right answer, but
computers are not so good at this.

-- Joseph Eisenberg

On 4/6/20, Martin Koppenhoefer <dieterdreist at gmail.com> wrote:
> Am Mo., 6. Apr. 2020 um 14:00 Uhr schrieb Kevin Kenny <
> kevin.b.kenny at gmail.com>:
>
>> That would also allow us to address Joseph Eisenberg's objection (in
>> the talk page on the WIki) that the proposal violates the 'one object,
>> one tag' principle.
>
>
>
> there is no such principle (AFAIK a principle like this is tried to adhere
> to in OSM-Carto, where they try that one tag is supported for displaying
> "one kind of thing" (and to which there is at least the exception of
> highway=footway and highway=path with foot=designated, etc.). But this
> isn't a general OSM principle (where we also generally try to avoid
> different tags with the same meaning, but accept their creation if there
> are reasons).
> The principle in OSM tagging is "One feature, one OSM element", and it will
> always work out if you apply the "correct interpretation", because the real
> world doesn't have "features", they come into existence with us defining
> what a feature is. E.g. a School delimited by a fence could be seen as 2
> features: a school and a fence, or it could be seen as one feature, a
> fenced off school.
>
> Cheers
> Martin
>