[Tagging] Issues relating to URIs and tagging
danstowell+osm at gmail.com
Tue Apr 1 16:31:01 UTC 2014
2014-04-01 16:29 GMT+01:00 Andy Mabbett <andy at pigsonthewing.org.uk>:
> Hello everyone,
> This is my first post to the list, which I've just joined, but I've
> been a mapper for a few years and some of you might remember me as
> compere at last year's State of the Map.
And well done indeed!
> Yesterday, I met with the W3Cs' "data on the web best practice"
> working group. At their request, I gave a talk on the use of URIs
> (particularly linked data URIs) and related tags, in OSM.
> I described, and we then discussed, how we tag entities in OSM, using
> UIDs but not necessarily URLs, and issues facing data users who need
> to resolve those UIDs back to URLs; for example:
> openplaques_plaque = 1536
> To that end, I've just modified [[Template:KeyDescription]] by adding
> two parameters:
> for "website" and "url_pattern"
That URL doesn't seem right. I think you mean
> of an example of how they're intended to be used (the label display
> needs tweaking).
Tell me if I've misunderstood you, but you're proposing that the
url_pattern given in the wiki "infobox" KeyDescription is intended to
be machine-readable, in the sense that a third-party data consumer can
plug url_pattern together with the actual key-values found in OSM and
automatically find the URL for something? If so, the idea is
intriguing and I think it's a nice lightweight thing we can do.
I have a small quibble which is please change it from "URL" to "URI",
since I think the latter is the more appropriate concept. We're aiming
to interlink _identities_ of items really, for the machines.
> The model used there fails with Wikipedia links,
> expressed as "en:Example", because the equivalent URL is
> <https://en.wikipedia.org/wiki/Example>. Any suggestions for dealing
> with that?
I don't see a plausible way of dealing with this that wouldn't be a
crazy hack. So I'd recommend that data re-users will simply need to
treat this as a special case if it's important to them. (I've always
thought the wikipedia tag would have worked better as
"wikipedia:en=Example" -- in that case, your template approach would
have worked fine.)
> They were very impressed with the inclusion of Wikidata IDs
> The sooner we move that from "Talk:Proposed_features/" to "Key:", the better.
Wikidata proposal looks good to me.
> Other issues which are unhelpful to data re-users include keys with
> missing documentation; redundant keys ("Key:openplaques_plaque" vs
I have never seen these tags, but there are very few uses - this
example is probably really easy to consolidate into one tag.
The harder cases will - as discussed in recent threads on this list -
will remain in a state of productive controversy for a long time to
come! Sorry, data re-users, but that's wiki-life for you.
> ambiguous keys ("ref=1234" - ref in whose database?)
That's an interesting question. "ref" is widely used, and generally
used quite coherently, _but_ its meaning is contextual on other tags.
For example, "amenity=post_box" & "operator=Royal Mail" tells you
where to expect the ref to point. I wonder if "operator" sets the
context in many other cases? (I accept, of course, that many objects
aren't tagged with operator.)
> and the perennial problem of the lack of stable URIs for entities in OSM. I have yet to solve that one...
OSM objects are not stable, same as Wikipedia articles. For Wikipedia
they provide partial stability through long-term historical "oldid"
links and redirects. I don't think tagging (i.e. this list) can solve
the permalink problem. It needs osm.org to provide a URL scheme that
allows people to link to a specific historical _version_ of an osm
object. We already provide direct links to changesets and to object
histories, so the data is all there.
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