[Talk-GB] UK cities

[Ed Avis]

Tom Hughes <tom at ...> writes:

>>If you map an area, that
>>forces the choice of whether your object is intended to represent the
>>City of London, or Greater London, or whatever.
>
>The problem with that approach is that concepts like "town" and "city"
>do not have well defined boundaries in the UK.

Implicit in my argument for mapping areas was the assumption that
you'd want to map the official definition of city rather than the
informal one.  AFAIK, every city has a defined boundary, even if
nowadays it is no longer marked by a city wall.

For 'town' this is not so, and you could not take a strict approach there.

If you decide to map the informal view of where a city lies, rather
than its legal boundary, then you have a choice of picking an
arbitrary boundary or picking an arbitrary centre point.  Somehow in
OSM we are more comfortable with the latter, but it is hard to justify
from first principles.  By giving less information, a single point has
less scope for edit wars and is not going to fool users of the map
into thinking a hard boundary exists where one doesn't.  Nonetheless
applications might like to know about such informal boundaries ('you
are now entering Reading', announces the satnav).

--
Ed Avis <eda at waniasset.com>