by MarkC
13. October 2010 08:42
The postcode was invented in Britain, and we still have one of the best systems in the world. In only a few characters you can identify an address with a remarkable level of precision, and it is simple to remember, making it ideal for applications such as postcode lookup, geocoding and find-my-nearest. But have you ever stopped to think about what goes into a postcode and what it all means?
As an example, I'll take a look at our postcode at Data8, CH65 2HQ.
| CH |
65 |
|
2 |
HQ |
| Area |
District |
|
Sector |
Walk |
Area
The Area, made up of one or two characters, indicates one of 124 postal areas across the UK. Because the letters are usually related to a local major town or city, this is one of the aspects of a postcode that makes them so easy for people to remember.
District
The combination of the Area and District is known as the "outcode", and generally indicates a sorting office. Any mail addressed to that outcode will be delivered to that sorting office for delivery. Generally speaking, the higher the number the further away the address is from the centre of the major town indicated by the Area.
Sector
The Sector, always a single digit, indicates an area served by the sorting office. These numbers are usually allocated so that smaller numbers are around the centre of the town, while larger numbers are the more distant rural areas.
Walk
The Walk will normally indicate a street or part of a street in urban areas. Tower blocks may well have a walk to themselves, and larger companies can get their own as well. In more rural areas however, a walk can cover a much larger area. This is why satnav devices are more accurate in more built-up areas. The combination of Sector and Walk is the information used within a sorting office to direct the mail to the correct postman's round.
In addition to the postcode, each premise also has a "Delivery Point Suffix" (DPS). The combination of postcode and DPS uniquely identifies a mail delivery point, and it is this combination in barcode form you will see printed on virtually all envelopes delivered to your house.