[OSM-talk] Improving ref=* documentation

[Colin Smale]

> On 08/05/2021 5:02 AM stevea <steveaosm at softworkers.com> wrote:
> 
>  
> +1
> 
> On Aug 4, 2021, at 5:30 PM, Joseph Eisenberg <joseph.eisenberg at gmail.com> wrote:
> > Two of the principles on the "Good Practice" page suggest that the real-world information, as found on signs or other physical evidence, rather than the laws in the register office somewhere, are considered the primary source. This advice has been in the wiki for over 10 years: https://wiki.openstreetmap.org/wiki/Good_practice...

"Primary source" is not the same as "sole source." Where sources conflict, we exercise judgement. Which source is most likely to be "correct" in OSM terms?

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.

Could the use of "local_ref=*" help out here, to hold the locally visible ref that contradicts the official verdict?