[Talk-GB] PRoW Ref codes (WAS:Hampshire Rights of Way Data released under OS OpenData licence)

[Colin Smale]

On 08/06/2012 16:02, John Sturdy wrote:
> On Fri, Jun 8, 2012 at 2:07 PM, Gregory <nomoregrapes at googlemail.com> wrote:
>> Is it not sensible to use the reference format of the place you are in,
>> rather than create some sudo standard?
>>> A web application I'm developing straddles many counties.  So I've decided
>>> to adopt the scheme:
>>>    code-for-council:code-for-path-adopted-by-council
> I think this is a way of doing what you suggest, i.e. using the
> reference format of the place you're in (along with the necessary
> indication of what place you are in).
>
> An alternative would be to use the council's own code, and then in
> another tag (or in a relation, see
> http://wiki.openstreetmap.org/wiki/Relations/Proposed/Is_In)
> indicating which county it is in.  But that seems a roundabout way of
> doing it, harder both to use and to map.
>
That is exactly what the concept of namespaces/value domains is designed 
to address. Counties won't check with each other about uniqueness of the 
value, so it's only guaranteed unique and unambiguous within the context 
of a certain county. Hence, the ref must be accompanied with an 
indication of which county generated the ref. So ref=organisation:num is 
one way, ref:organisation=num is another. Just think of what happens in 
the case of a new path: who or what generates its ref?

It would be nothing short of best practice to include the organisation 
in the tagging. Just like the principle which says that amounts are 
never recorded in financial systems without a currency code and 
timestamps must always have a timezone - to avoid all possibility of 
ambiguity.

Colin