Re: [backstage] Best Mapping API

[Barry Hunter]

Postcodes are for delivering letters - they're not a standardised way to locate things - the coordinates relate to the postmans walking route and can change from time to time.   I don't think that is strictly true. In the case of the OS Code-Point product which provides locations to 1m precision is actually the mathematical 'center' point for all the buildings served by that postcode. You can use Address Point which as the center of the building for each address served by a postcode so can be even more accurate. (Code-point is derived from Address-Point)   On some strange shaped postcodes, the calculated centre point can be quite abstract, but will rarely be more that 100m from any of the buildings so is quite useable.   The location specified in the Postzon product (from the Royal Mail) that is quoted to 100m accuracy I'm not so sure about, but I think is derived in the same way.   The postcodes are designed for post delivery so the distribution and ordering of different postcodes are not in geographical sensible order or layout. But the location later defined for the postcode should be quite useable!   Barry   - www.nearby.org.uk - www.geograph.org.uk - www.trigtools.co.uk -