[OSM-talk] administrative boundaries and is_in

[Andy Allan]

On Jan 9, 2008 8:44 PM, Robin Paulson <robin.paulson at gmail.com> wrote:
> can someone explain a few things about the way boundaries work, and
> their relation to the is_in key?
>
> as far as i can tell, when a location (say the suburb of balham, in
> london) is added to the map, the is_in tag needs to be set, multiple
> times. in this case, it would be set as follows:
>
> is_in:Westminster (...i think)
> is_in:greater london
> is_in:england
> is_in:united_kingdom
> is_in:British_Isles
> is_in:Great_Britain
> is_in:Europe
> ...etc.
>
> which seems counter-intuitive, not to mention requiring huge amounts
> of work. do we set this for every item - roads, churches,
> supermarkets,....thousands of other items?
> is there anything underway to enable OSM to calculate where an object
> is, based upon knowledge of administrative boundaries - after all,
> they are only a polygon-shaped bounding box?

I think it's worth remembering the history of all of this, since it
will help explain things. The is_in tag predates the ideas of having
wide-spread administrative boundaries (something which I've only seen
happening in the UK over the last 5 months or so) and certainly
predates relations by a long way.

They are probably still useful for some cases, but as you can see
other mechanisms for specifying hierarchy and relations may be more
appropriate nowadays.

Cheers,
Andy