[Talk-GB] Places and postcodes -- nodes/areas?

[Craig Wallace]

On 11/09/2012 10:47, Matt Williams wrote:
> On 10 September 2012 23:07, David Fisher <djfisher81 at gmail.com> wrote:
>> My other (related) question is to do with postcodes. Some postboxes nearby
>> have been tagged not only with "ref=xxx" (containing the first part of the
>> postcode plus a reference no.) but also "postal_code=xxx" (again containing
>> the first part of the postcode), meaning that, again, a lot of streets &
>> POIs become identified by Nominatim with this postcode (e.g.
>> http://www.openstreetmap.org/browse/node/363996567).  Should *all* postboxes
>> be tagged with "postal_code" in this way?  What about streets themselves?
>> For streets, does the (first part of the) postcode need to be displayed on
>> the street sign for this to be done?
>
> The 'ref' part will be directly from the postbox label itself. I'd
> imagine that the majority of the postal_code entries are from
> http://dracos.co.uk/made/locating-postboxes/. Unless we have another
> source of postcode data I'm not aware of? Even with the Dracos stuff,
> I'm unsure of the licensing details.

I think most of the postal_code tags on postboxes are just based on the 
ref. eg if the ref on the box is "SE25 29", it is assumed the postbox is 
in the SE25 postcode, so it is tagged as postal_code=SE25.

Though I'm not sure how helpful this is. It may not always be accurate - 
I have seen a few postboxes with a ref for one postcode, when they are 
clearly in a different postcode area. And even two adjacent postboxes 
with refs for different postcodes.

Maybe this is just Royal Mail mixing up the labels on postboxes. Or 
maybe the postbox is emptied as part of a different delivery route. 
Especially meter mail postboxes - they often seem to have 'wrong' refs.

Craig