Anthony wrote: > Hi Frederik, > > What are the sources for the post code areas? How often are they > updated? How are they defined (by reference to houses, by reference to > geographical features, by lat/lon, something else)? Will this data be > integrated into other OSM data, or is it basically just a separate layer?
Looking at the post code data that has just been 'open sourced' by the UK government I am beginning to realise part of the problem here. We are trying to create a generic solution when in reality there are distinct differences country to country. "How are they defined" ... In the UK by a list of house numbers and names which the Post Office still maintains copyright on, so the OSOpenData 'postcode' information only has a lat/lon reference (codepoint), and NO address data. One can draw areas around the group of houses that form a postcode, but that is not the right way of handling them. The OSOpenData list needs to be augmented with a lower layer of 'house' objects. ANY boundary drawn around that group will be arbitrary From what I am seeing Canada works a similar way? But many other countries DO define an area for 'postcodes' which in reality are simply fairly large post areas defined as such, and do not (as yet) go down to define postcodes for smaller groups of buildings. The US ZIP code system has a nice hierarchy of AREA information? But even it's ZIP4 code is not 'defined' by reference to a simple list of house ID's Bottom line ... create 'areas' for information that is actually defined as an area, but keep finer detail in the format it is defined in? Returning to Frederik's original question ... http://en.wikipedia.org/wiki/List_of_postal_codes_in_Germany on the whole covers it quite nicely. German post codes are defined by area - which do not match state boundaries. BUT a common aspect to all of this is the hierarchy of course detail, with - in the case of Germany - 10 areas each divided into 10 sub areas. Just like the UK has a number of large areas defined by letters or letter pairs, each of which is sub divide, BUT the 'areas' so defined only loosely enclose a number of individually identified properties. So we have a hierarchy of boundaries - which may or may not correspond to administrative boundaries - but which ARE as difficult to draw. Perhaps they do need their own 'layer' of data, the top rung of which is 'country' which then drills down through a set of larger and smaller post_boundary data. An 'international' post code would then be prefixed with the country code so that one knows exactly where in the world one is when adding a 'postcode' to a location? I have always maintained that we need hierarchic lists overlying the physical data so that one can search for locations in that tree, and postcode is just another fairly consistently defined tree? -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk// Firebird - http://www.firebirdsql.org/index.php _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
