[Tagging] How to overcome lack of consensus

François Lacombe francois.lacombe at telecom-bretagne.eu
Mon Sep 16 18:32:41 UTC 2013

And don't forget power=line vs power=cable :) :) :) :) :)


*François Lacombe*

francois dot lacombe At telecom-bretagne dot eu

2013/9/16 Peter Wendorff <wendorff at uni-paderborn.de>

> Hi,
> let's tackle the "problems" you mention one by one:
> Am 16.09.2013 16:41, schrieb Matthijs Melissen:
> > Dear all,
> > [...] The lack
> > of consensus does cause problems for the Openstreetmap community, though.
> Most often it only cause problems for consumers of our data, not for the
> mappers. Nevertheless you're right, it would be good to have clearly
> defined rules in some cases.
> > Therefore, it would be good to have ideas or procedures on how to create
> > consensus.
> >
> > There are currently quite a lot of OpenStreetMap features for which there
> > is no consensus on how to tag them. Some examples (but I'm sure there are
> > many more):
> > - What is the difference between highway=footway and highway=path?
> A footway is a footway, mainly or only dedicated to people using it by
> foot. Any exception should be stated as such (e.g. bicycle=yes if bikes
> are allowed).
> A path is a path - which might be used by pedestrians/walkers, but not
> only and not necessarily - you may guess what's allowed and what's not,
> but you should not rely on anything without taking additional tags into
> account.
> That's for you as a mapper.
> For the data consumer that might be different:
> - a path may be estimated to be accessible by foot if not stated
> otherwise, because (!) there's not enough detailled data to be able to
> rely only on existent data.
> > - What is the right scheme for tagging public transport?
> (I'll skip this)
> > - Is an unsurfaced residential road a track?
> At first: unsurfaced? there's no surface? should be impossible because
> if there's no surface then there's no road ;)
> If you mean unpaved: it depends how you map it.
> I personally would add a residential as highway=residential, independent
> on the surface. In many development countries residentials are nearly
> never paved, so that's only a guess (depending on the region) if not
> stated otherwise.
> A residential therefore IMHO should be highway=residential, and if you
> want or if you think it's useful as it's not what anyone would estimate
> there, add surface=* to it, like surface=unpaved, surface=mud,
> surface=sand or whatever matches.
> Again: On the consumer side a residential e.g. in most parts of Europe
> would usually be guessed as being paved with paving_stones, asphalt or
> concrete, but that's only an estimation again, so to make it clear, map it.
> > - Should we use shop=betting or shop=bookmaker?
> > - Should we use shop=fishmonger or shop=seafood?
> > - Should we use office=estate_agent or shop=estate_agent?
> no idea - never used it.
> > - Should we use shop=tailor or craft=tailor?
> Depends...
> Is there a tailor inside? or are they only selling what a tailor produces?
> Is the shop directly connected to/containing the workshop? or is there a
> shop selling the stuff and another place where it's crafted?
> The craft tag is there to get exactly that difference, I think.
> A better example might be confectionary.
> A shop=confectionary sells confectionary, but it does not necessarily
> produce them, there does not need be someone making them - instead they
> could by it.
> A craft=confectionary on the other side may sell their own products - or
> not.
> That leads to three possible combinations, all valid and all telling
> different things:
> - shop=confectionary + craft=confectionary: selling and making
> confectionary
> - craft=confectionary: making confectionary, but not necessarily selling
> them via a shop (they may sell them via internet, or only to other
> shops, or they may sell it in their shop somewhere else)
> - shop=confectionary: they buy their stuff somewhere and sell it to you.
> > The lack of consensus becomes clear by the fact that there are
> > discrepancies between documentation on the wiki, the outcome of a voting,
> > actual use (as documented on Taginfo, for example), and what editors and
> > renderers support.
> >
> > The lack of consensus creates several problems. These problems include
> the
> > following.
> > - Multiple parallel tagging schemes and unclear documentation creates
> > confusion for newcomers.
> That's true, but how do you want to tackle that without limiting the
> freedom to invent new and better tags?
> The multiplicity of parallel tagging schemes comes in where there's no
> best variant - or where there's a lack of documentation.
> Lack of documentation: go and document ;)
> Confusion to newcomers: Explain it. Explain why there are several
> possibilities, explain that they themself may invent own tags, and give
> them taginfo and the wiki to search for reasons to use one or the other
> variant.
> > - Users are often advised not to follow the documentation on the wiki,
> and
> > to look at Taginfo instead. This makes the wiki useless. It also leads to
> > the fact that hardly anybody bothers to edit the wiki anymore.
> True: Do you have any idea how to solve the problem of documentation not
> reflected by practice or the other way around?
> In general both has to be seen. A documentation in the wiki might be
> outdated - then mappers should avoid following it, it might be missing,
> and it might be plainly wrong. On the other side sometimes there is good
> documentation but the documented features are very rare or the tagging
> is new, so that there's not yet "current usage" you could find on taginfo.
> Therefore both is necessary, and yes, it's not easy to see both and to
> decide what to do, but how to solve it?
> If you would put the rule to follow documentation "only", what if Mapper
> Max invents a new tagging scheme, documents that but nobody uses it,
> because it's a bad idea?
> If you would put the rule to follow actual usage, what if a group of
> mappers get a really great new tagging scheme, documents it, but it's
> not used yet? Nobody would (and could, following your rule) use that new
> scheme as it IS not used yet.
> Both is necessary, and the connection between wiki and taginfo (taginfo
> linking the documentation and the wiki showing stats from taginfo) is
> one step to the right direction.
> The next step which has to be worked on continuously is to extend and
> polish documentation in the wiki.
> regards
> Peter
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