[Talk-GB] [OSM-talk] Improving ref=* documentation

Mateusz Konieczny matkoniecz at tutanota.com
Thu Aug 5 11:25:02 UTC 2021




Aug 5, 2021, 10:38 by colin.smale at xs4all.nl:

>> On 08/05/2021 10:07 AM Mike Baggaley <mike at tvage.co.uk> wrote:
>>
>>  
>> >If you have a road which is signed (for example) "A12" for almost its
>> entire length, but somewhere there is a one-off sign that says "A21", do we
>> tag that bit of >road as "A21"? Over what length? Or do we map following our
>> cognitive processes, and assume that the sign is erroneous?
>> >
>> >If you have a road that in fact used to be the B2009 but was declassified
>> years ago, but somewhere along its length there is a rusty fingerpost in the
>> hedge that >has the old number on it, does that road magically regain its
>> number from 30 years ago?
>> >
>> >If we are not going to let many decades of data modelling experience get in
>> the way of our tagging schema, we accept that there is only one "ref" for a
>> road. How >we judge which one to choose is what we are discussing here. Most
>> arguments seem to revolve around a use case whereby a car driver is
>> navigating, looking at >signs to help decide which way to go. The human
>> brain is good at glossing over mistakes that appear obvious, but that's no
>> reason to propagate them.
>>
>> I suggest using name:signed and ref:signed to hold incorrectly signed
>> values. You can then have name:signed=yes, name:signed=no and
>> name:signed=<signed name>. I would suggest that if used to hold a value
>> other than yes/no, then source:name and/or source:ref ought to also be
>> specified so that it is clear why the name/ref is not the same as the sign.
>>
>
> Problem solved, then. Thanks for the clear and pragmatic solution. ref and name carry the official, proper values, and if a sign disagrees, put that in name:signed or ref:signed together with information about the sources.
>
> What's not to like?
>
> This allows two different renderings to be derived from the same data - one using the official values, and one using the "as-signed" values. The consumer can choose, according to their specific use case. We provide the data for both.
>
Note that we have also https://wiki.openstreetmap.org/wiki/Key:unsigned_ref for cases
where ref is assigned but never signed with a clearly visible reassurance marker.

(for some reason local road authority may post some barely visible signs, but they are
unreadable even while cycling and invisible when driving and noone uses them to
identify roads, such codes are appearing only in the  official documentation
See https://wiki.openstreetmap.org/wiki/File:Barely_signed_road_reference_code.jpg
where unsigned_ref is fitting
Though I admit that unsigned_ref is a poor name for one that can be actually signed
by some weird road authority officials... But noone really expected that.
)
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