[OSM-talk] OSM relation ID property in Wikidata

Paul Norman penorman at mac.com
Sat May 4 22:24:09 UTC 2013

> From: Mike [mailto:mike.cuttlers at gmail.com]
> Sent: Saturday, May 04, 2013 1:36 PM
> To: talk at openstreetmap.org
> Subject: Re: [OSM-talk] OSM relation ID property in Wikidata
>  > I am however concerned that
>  > if more people simply assume that the status quo is there to stay
> ("IDs  > are stable enough"), this will put pressure on *us* and limit
> our  > flexibility in the future.
> But, what is the point if ID's are not stable?
> How can we externally link to the data and make sure link will stay
> valid in time? I am not talking about URL links but links to objects
> (which, obviously, is done by object ID).

A link to an OSM object will remain a link to an OSM object, but that's not
very helpful.

An OSM ID will normally correspond to the same physical object for all of
its versions, unless its deleted. There is no guarantee, but it allows you
to say that if node 123 is not deleted then it is probably Joe's coffee
shop. It doesn't allow you to say that Joe's coffee shop is node 123.

A physical object will not always correspond to the same OSM ID. It is this
last property that matters for external links. As an example, a particular
Lowe's home improvement store near me used to be OSM node 1498097430 and now
is OSM way 136961700. When I get new imagery for the area and re-trace the
building depending on what is easiest I may end up creating a new way.

Relying on the OSM representation of some real-world object to maintain the
same ID is wrong. There is no property of OSM IDs that allows you to say
that Joe's coffee shop will continue to be node 123.

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