Mystery In The UK

I’m currently working on a webapp that will allow every country to participate. the content is locally consumed. I’m attempting to build a database to hold all the information, in a structured way. I’m confused by the  country relationships of the UK. I’m in the USA, so I’m not sure what the typical experience is for a UK citizen. There are four countries: England, Wales, Scotland, and North Ireland. These four countries, have formed an entity called “United Kingdom”, or UK for short.  Plain old ‘Ireland’ is a separate country. There is another entity called “Great Britian”, which refers to the countries England, Wales, and Scotland (source: DirectGov).  There’s an organization ISO that maintains global standards. One of the standards is ISO 3166-2, which is a list of country names, and their 2 character abbreviations. Looking at this list of country codes and names, the United Kingdom has the code of ‘GB’. Huh?  More confusingly, the countries England, Wales, Scotland, and North Ireland are all without their own 2 character codes. I guess the real question is “Who’s on first?“. Let’s hold off on that issue for a moment, and look back to my original problem. I’m unclear as to how I should model the relationship between the UK, the individual countries of the UK, and their cities. Let me give you an example. I live the United States, in the state of Washington(WA), in the city of Seattle. So my record would be like this: country=US, state=WA, city=Seattle. Given that, lets do an example for London. Three examples come to mind. The first captures the most information: country=UK, state=England, city=London. This one is appealing as it captures the most information in an existing structure. The second just removes England from the state field: country=UK, state=null, city=London. The third uses England for the country country=England, state=null, city=London. I’m considering this one because I know that England is a country, so it’s technically correct. Do people who live in the UK, look on web forms for UK, then their own specific country? Or do they look for their specific country, then UK? What’s the convention most users expect? Is there another territorial breakdown I’ve missed?  I know of postal codes. I appreciate any feedback you can provide. UPDATE 2009-FEB-21: Everybody’s feedback was very helpful, particularly Gary Gale (@vicchi) who just happens to be Head of UK Engineering at Yahoo Geo Technologies (@yahoogeo). Let’s recap of the things I’ve learned. First ‘United Kingdom’ is what users search for. It’s also the name that appears in the ISO 3166 list. So I can safely use it. Second, people never look for things by their individual country (England, Scotland, etc) – partly because of the previous point, and partly because postcodes are so informative, they can be used to pre-populate other fields like city and county. Third, the ‘county’ is what people typically use to filter things.  There are actually two sets of county information – administrative and postal. The web apps I’m writing are for people and not the government, so I’m going to use the postal counties. In summary, Mr Gale said “if you’re designing a web based mechanism for addresses you’d use the country, the county and the town followed by the street address and our Postal Code, the equivalent of the US ZIP”. Nice! Pragmatic and simple. Thanks again everyone. It’s been illuminating.