[OSM-talk] OSM relation ID property in Wikidata

[Tobias Knerr]

Am 06.05.2013 23:55, schrieb Peter Wendorff:
> Am 06.05.2013 23:07, schrieb andrzej zaborowski:
>> If you're not adding those historical entities to OSM (or a similar
>> database like that historical osm once discussed) then there's no
>> issue with linking to Wikidata because there's nothing to be linked.
> 
> Why not?

It wouldn't add any information. The hospital should be linked to the
building _within_ Wikidata anyway because there are more properties that
can be attached to a building than just a OSM building outline.

So if we connect the OSM building and the Wikidata building, then the
hospital is already (though Wikidata) linked to the OSM building, too.

>> If it doesn't occupy the entire building then you can probably add the
>> museum tag on the building geometry but later once you want to add a
>> wikidata tag you'd probably split it out like you'd split a street
>> object when you want to add an attribute that applies to a part of the
>> attribute.  If you're into indoor mapping then you'd draw the museum
>> outline separately anyway.
> so you propose to split it up because of an external ID you propose to
> add...
> While I in general agree that objects of osm are split when they get
> mapped in more detail (like in this example), I'm not happy to do that
> for the reason to enable matching to external references.

Using the same OSM element for two distinct features actually
contradicts a strict one feature, one OSM element principle. We do it
anyway because it's convenient, but as soon as you want to add the same
tag - whether it's name, opening_hours, or wikidata - to both features,
you create two separate elements.

That's not a special treatment of external IDs, but consistent with
other tags, and using two separate elements is semantically better anyway.

> and it's not working for opening_hours either afaik; usually we split
> the pois in these cases.

Exactly.

> Wikidata links are harder to maintain, nearly impossible to check
> (without opening the page), while wikipedia links have meaningful names.

YMMV, but I always open Wikipedia links to check whether they are
(still) correct.

> Therefore I personally oppose currently to reference wikidata entities
> from osm objects; at least where no good rules exist where and when to
> link which types of objects, and which not.

I think a good rule to start with would be: If there is a Wikipedia or
Wikidata entry about that particular feature *itself*, then it can
always be linked (using the appropriate key).

Such links cannot possibly be replaced with links within Wikidata, and
there is a limited number of them. With the namespaced links, however,
we indeed get an essentially unbounded number of potential links and I
don't know a good rule for these atm.

Tobias