While we're on postal-code formats, those used in the U.K. are very unusual.
They're written as two parts, e.g. NR27 9EJ. The first part is the "outward" code, used to get mailed letters to the correct regional sorting office. In this case the NR means Norwich region. NR1, NR2 etc. are actually within Norwich City, while the higher numbers cover the surrounding part of the country.
The second part is the "inward" code and narrows down the delivery address to within a single street, or a group of several houses. In theory, if you just wrote the postal code and house name/number, then a letter should get there.
The 4- or 5-figure codes used in Australia, France, etc. are much simpler! In the French system, for example, the first two digits of the postal code specify the "departement" (like a county). The same set of two-digit codes are found at the end of car license plate numbers, e.g. 16 = Charente, 75=Paris, etc.
