[OSM-dev] JOSM: Several tags with same key

Marcus Wolschon Marcus at Wolschon.biz
Sat Apr 4 05:42:51 BST 2009


2009/4/3 Pierre-André Jacquod <pjacquod at alumni.ethz.ch>:
>> this sort of thing already exists for banks, but is tagged as
>> amenity=bank, atm=yes. you could easily adopt this for other types as
>> well: shop=supermarket, atm=yes.
> Ok, I see, something like:
> amenity = post_box
> atm = yes
>
>> while stefan is right (there is no technical reason why we can't
>> support duplicate tag keys whilst ensuring the tags themselves are
>> unique), the pragmatic approach is to recognise that most clients and
>> other bits of OSM software already use some sort of unique keyed map
>> to store tags.
>
> Ok I can understand this approach. I am currently gathering statistics
> (currently limited to austria and switzerland) in order to show how key
> / value are used and I have the following observation:
>
> As drawback, I see the following point: I have a characteristic (in this
>  case post_box) once as a value, the second time as a key (atm=yes).
> This means I am not more able to find easily all atm, e.g, since
> sometime the value will appear in the value side (if this is alone) but
> could / would also appear on the key side... And I have to check that I
> do not have a atm = no (you never know...)

Yes,
I also see this as an error in the tagging-schema.
We have way too many values for "amenity" so these collisions
happen all the time. It`s not just bank+atm, it is also
hotel+restaurant and many others.
This way of tagging amenities simply grew without any regard
for what was technically possible (most editors never properly supported
multiple values for a key, thus noone was to use them as their work
could be destroyed at any moment).

Marcus




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