Comments:"Falsehoods programmers believe about addresses"
URL:http://www.mjt.me.uk/posts/falsehoods-programmers-believe-about-addresses/
Addressing is a fertile ground for incorrect assumptions, because everyone’s used to dealing with addresses and 99% of the time they seem so simple. Below are some incorrect assumptions I’ve seen made, or made myself. (If you want to look up an address for a UK postcode or vice-versa to confirm what I’m telling you, try the Royal Mail Postcode Finder)
Customers will have a fixed address with a fixed location
A developer just a few seats from me recently brought a house boat with the intention of using it as her primary residence. Needless to say, boats can move!
An address will include a state in the US sense.
Counterexample: Any address in the United Kingdom.
An address will start with, or at least include, a building number.
Counterexample: Royal Opera House, Covent Garden, London, WC2E 9DD, United Kingdom.
When there’s a number in an address, other than in the postal code, it’s the building number.
You also get flat numbers, suite numbers, floor numbers, unit numbers, and organisations with numbers in their names. For example: Flat 18, Da Vinci House, 44 Saffron Hill, London, EC1N 8FH, United Kingdom
When there is a building number, it will be all-numeric.
Counterexample: Flat 1.4, Ziggurat Building, 60-66 Saffron Hill, London, EC1N 8QX, United Kingdom
Alternative Counterexample: 1A Egmont Road, Middlesbrough, TS4 2HT
No buildings are numbered zero
Counterexample: 0 Egmont Road, Middlesbrough, TS4 2HT
When there’s a building name, there won’t be a building number (or vice-versa)
Counterexample: Flat 1.4, Ziggurat Building, 60-66 Saffron Hill, London, EC1N 8QX, United Kingdom
Addresses will only have one street
The Royal Mail have what they call a ‘dependent street’ - for example: 6 Elm Avenue, Runcorn Road, Birmingham, B12 8QX, United Kingdom (Runcorn Road is the street, Elm Avenue is the stubby ‘dependent street’ and isn’t unique within the city. Google Maps )
Counterexample 2: Rogue Hair, 1 Hopton Parade, Streatham High Road, London, SW16 6EP (Streatham High Road is the street. Hopton Parade is a little row of shops on the road - Google Maps )
Addresses will have a street
The Royal Mail will deliver to certain premises by name, such as farms and cottages. Example: Oakland, Fairseat, Sevenoaks, TN15 7LT, United Kingdom (Fairseat is the town - this is actually on Vigo Road. Google Maps )
Addresses will have something other than the organisation and city name.
Large recipients of mail are sometimes addressed by organisation alone - for example: Electoral Reform Society Ltd, London, N1 1RS, United Kingdom
Addresses will have a reasonable number of characters - less than 100, say.
Not when organisation and department names can be included in addresses! For example: Department For Environment Food & Rural Affairs (D E F R A), State Veterinary Service, Animal Health Office, Hadrian House, Wavell Drive, Rosehill Industrial Estate, Carlisle, CA1 2TB, United Kingdom
Another example: The Gynaecology Cancer Research Unit, Department of Obstetrics & Gynaecology, St. Bartholomews & The Royal School of Medicine & Dentistry, Charterhouse Square, London, EC1M 6GR, United Kingdom
Addresses don’t contain commas (so I can replace newlines with commas then commas with newlines and get back to where I was)
Addresses can contain organisation names, and organisation names can contain commas. For example: Society of College, National & University Libraries, 102 Euston Street, London, NW1 2HA
Addresses don’t change
Addresses can move between counties and administrative districts. For example, I used to live in the county Gwent, but that no longer exists. Addresses may also be assigned new postcodes.
Five lines and country will cover all cases.
You’ll need 8 lines and country to deliver to: GB Technical Services, Unit W7a, Warwick House, 18 Forge Lane, Minworth Industrial Park, Minworth, Sutton Coldfield, B76 1AH, United Kingdom
The user will know their postal code/zip code.
Most users will, of course, but I’ve seen incorrect postcodes on corporate letterheads! Misreading handwritten postcodes seems like a common one.
A single postcode will only cover a few tens of addresses / customers
Mostly this is reasonable in the UK, but there are certain exceptions. For example CV4 7AL is the postcode of the University of Warwick - one postcode for 6,000 students living on campus, and academics/administrators working on campus.
Also, if your customers get things delivered to them when they’re on holiday, lots of customers may have the same holiday parks on their accounts.
Some addresses correspond to ‘flexible office spaces’; the Royal Mail lists more than 90 organisations operating out of Tower 42, 25 Old Broad Street, London, EC2N 1HQ
Update: Victor Nicollet points out French postcode 75015, representing the XVth arrondissement of Paris, covers over 230,000 people
A building number will only be used once per street
The difference between 50 Ammanford Road, Tycroes, Ammanford, SA18 3QJ and 50 Ammanford Road, Llandybie, Ammanford, SA18 3YF is about 4 miles (Google Maps).
A road will only have one name
Many different roads, from Goswell Road in London to Regent Road in Edinburgh, make up the 410 mile A1. And while there may only be one “1 Goswell Road” and only one “1 Regent Road” there are multiple buildings numbered 1 on the road designated A1.
Roads may also be named in multiple languages. For example, in Ireland roads may be named in both English and Irish
A road will have a name
Plenty of roads like driveways, onramps and the aisles of carparks don’t have names.
A building will be within a few hundred meters of a public road
Buildings like farms and country houses can be at the end of a private road or driveway several hundred meters long.
An address will have a postcode
Update:How did I miss this one? Richard Fletcher, Lee Hosty, Paul O'Nolan, Simon Diab, Tony Finn, Donal Maccarthy and Donovan all pointed out countries like the Republic of Ireland have addresses without postcodes, or only have postcodes in certain parts of the country.
An address can be expressed with a single country
Update:Matthieu Valleton got in touch to point out his address on Kerguelen Island (Google Map), a French territory in the Indian Ocean, his address was District de Kerguelen (island), Terres Australes et Antarctiques Françaises (territory), via la Réunion (indicates where the mail should be routed through), France (country)
An address will be comprised of road names
Update:Kirk Kerekes spent several years using an address of the form "2 mi N then 3 mi W of Jennings, OK 74038" which regularly got successful deliveries.
An address will only have one postcode
Update:Graham Lee points out DVLA Swansea (that's the whole address), where different departments are identified by postcode: V5Cs are processed at SA99 1BA, driving licences at SA99 1AB and so on.
An address will exist in the country's postal service's database
Update:Simon Westcott points out databases are only released periodically, so it's not unusual for new buildings to be omitted.
An in the country's postal service's database will exist
Royal Mail and Ordnance Survey data can contain demolished buildings, and buildings currently under construction. Temporary postcodes can even be assigned to building sites!
Do you have an example that belongs in the list above? Drop me an e-mail, at website@mjt.me.uk