[Talk-GB] UPRN wiki page

[Mark Goodge]

On 17/11/2020 14:10, Jez Nicholson wrote:
> Whilst i'm here, am I correct that a UPRN can *only* be on a single 
> thing? So anything in 
> https://taginfo.openstreetmap.org/keys/?key=ref%3AGB%3Auprn#values 
> <https://taginfo.openstreetmap.org/keys/?key=ref%3AGB%3Auprn#values> 
> more than once is an error?

There is a one to one correspondance between UPRNs and addressable 
objects (in either the PAF or AddressBase). A single mappable entity may 
contain multiple addressable units (eg, a block of flats), so there can 
be multiple UPRNs on a single OSM object, since we don't normally 
subdivide buildings into individual units unless it can easily be mapped.

But the reverse isn't true. A single UPRN can only correctly be assigned 
to a single object. If it's being assigned to multiple objects then 
there's likely to be an error somewhere.

But, having said that....

> ...or can a road have a USRN *and* a UPRN?
Yes. And, in this particular case:

https://taginfo.openstreetmap.org/tags/ref%3AGB%3Auprn=10071171668

(follow the Overpass turbo link to see it mapped)

what we have is what, from a mapping perspective, is a single road 
(Glazebury Way), but that comprises multiple OSM ways. So it's not 
unreasonable to add the UPRN to all the ways which make up the road.

Whether a road has a UPRN as well as a USRN is a bit inconsistent. As a 
general rule, roads which existed before UPRN/USRN addressing was rolled 
out will only have a USRN allocated. But new roads that are built as 
part of a new development will, typically, have a UPRN as the road 
usually exists before the houses (or industrial units) accessed from 
that road are built. So the road has to have its own entry in the UPRN 
database.

It is complicated, and the published documentation isn't particularly 
comprehensive. I'm still getting my head round it!

Mark