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

[Colin Smale]

>     On 08/06/2021 5:02 PM Mateusz Konieczny via Talk-GB <talk-gb at openstreetmap.org> wrote:
> 
> 
> 
> 
> 
>     Aug 6, 2021, 13:26 by colin.smale at xs4all.nl:
> 
>         > > 
> >             > > >             On 08/06/2021 12:20 PM Mateusz Konieczny via Talk-GB <talk-gb at openstreetmap.org> wrote:
> > >             Aug 6, 2021, 12:13 by colin.smale at xs4all.nl:
> > > 
> > >                 > > > > 
> > > >                     > > > > >                     On 08/06/2021 11:23 AM David Woolley <forums at david-woolley.me.uk> wrote:
> > > > > 
> > > > > 
> > > > >                     On 06/08/2021 06:57, Jay Turner wrote:
> > > > >                     > Perhaps "ref:signed=poorly"?
> > > > >                     >
> > > > > 
> > > > >                     That's subjective and OSM doesn't collect subjective information.
> > > > > 
> > > > >                 > > > > 
> > > >                 Ahem... There are plenty of examples of (partially) subjective information in OSM. Tracktype and smoothness for example. Even highway=* gives rise to discussion from time to time, as one mapper's judgement differs from another mapper's. Only by reference to an authoritative source can all elements of personal judgement be eliminated from the equation.
> > > > 
> > > >             > > >             And even then we would run into problems as soon as there is more than one
> > >             "authoritative source".
> > > 
> > >         > > 
> >         There cannot be more than one "authoritative source" by definition.
> > 
> >         There can be indirectly authoritative sources, which are individually derived from the authoritative source and can potentially disagree with each other, as a consequence of a mistake or temporal considerations (update date/frequency etc). Such apparent conflicts can be resolved by reference to the authoritative source itself.
> > 
> >     >     With strict definition it turns out that most of what would be considered "authoritative source"
>     actually is not.
> 


>     UK has much better governance than average and is much richer than average, so maybe it
>     is quite rare to run into such issues. But it my experience it is common that supposedly
>     "authoritative source" is often mismatching with itself, reality, other supposedly equivalent
>     "authoritative source".
> 
I think you overestimate the UK... just look at its local government hierarchy, and the way that maps (or doesn't map) to places on the ground and postal addresses... It's a complete mess, the likes of which don't happen in countries in Europe that I know well - NL, BE, DE, FR at least.

>     And there is often conflict what actually is "authoritative source".
> 
>     Strict following of authoritative sources would result in plenty of misalignment,
>     invalid data, ridiculous data etc.
> 
An authoritative source, to my mind, is one that can be regarded as a single point of truth. Whether a road exists or not, i.e. whether there is a strip of tarmac at a given location, is proven definitively by its existence - anyone can verify that. But whether that road is called High Street or Bloggs Avenue is not decided by the general public, it is a matter of an official decision taken within a legal framework. The authoritative source for its name cannot be anything other than the official decision that gave the street its name. Following that decision, an order is given to fabricate street name signs, and mistakes get made at this stage as well. But a mistake is just that, a mistake. It does not override the authoritative source, if your are looking for *the name of the street*. On the other hand, if you want *the text on the road sign*, then feel free to propagate the typo - but don't misrepresent it as "the name of the street".

>     Actual example: some years ago firefighters in Poland ended using OSM data as source
>     as official authoritative source was
>      (a) unavailable to them - AFAIK it improved since then
>      (b) different administrative units had own databases, with roads on border between
>            them mismatching location. In other words, authoritative sources disagreed
>            where intersection of road and voiwodeship border is located - such as
>            https://www.openstreetmap.org/?mlat=50.32434&mlon=20.29192#map=19/50.32434/20.29192
> 
The road can be surveyed using accurate GPS - no need for any conflicts there.
As to the admin boundaries - I gather a voiwodeship is roughly equivalent to a province, so somewhere at national level there is probably some kind definitive map, or description, of where the boundaries lie, or am I wrong here? Can the provincial authorities make up their own borders?

The firefighters may have trusted their sources, in good faith, but that doesn't make them authorititave.
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