[Openstreetmap] Re: freeing the postcode database

[Christian van den Bosch]

Petter Reinholdtsen wrote:
> The postal codes seem to have different structures between countries.

For starters:

UK: a(a)n(n|a) naa - the initial alpha(s) are a mnemonic for city or 
region. All of Northern Ireland is BTn(n), despite containing several 
cities. London on the other hand is divided into several regions. Quite 
complex to parse/validate. Mnemonic look-up tables will be needed.

IE: n(n) - currently only used in Dublin; odd and even numbers are north 
and south of the Liffey respectively. One Dublin postcode, 6W, does not 
fit the given template. Postcodes also exist in Cork, which has at most 
half a dozen postcoded areas, but they are not in common usage. Proper 
street-level postcodes are to be introduced nationwide any year now :)

NL: nnnn-aa - the first two digits denote city or region; the remainder 
denotes the delivery route, down to street side and segment.

FR: nnnnn - the first two digits denote department, as also used for 
vehicle number plate suffix. Not street level.

DE: nnnnn - not street level.

BE: nnnn - not street level.

SE: nnn nn - not street level.

US: (aa) nnnnn(-nnnn) - the alphas denote state, the nnnnn seem to be 
low in the Eastern US, high in the West. The -nnnn suffix brings 
zipcodes down to street level.

CA: ana nan - accurate to street segment and side.

Christian / cjb

http://www.cjb.ie/