I'm sitting here in Oxfordshire and I'm preparing lots of packets and envelopes to send stuff to several of you American-type people, and I'm wondering about zip codes. Here in Britain, I believe the prosaically-titled 'post code', of two groups of three or four letters and numbers, will identify a house within say a hundred yards.

How closely can an address be located by zipcode alone? Why do some zipcodes have five numbers and then another four - I thought at first it was for more precise location in a big city, but I've just realised that one like that appears to be in the middle of a desert. And is it really true that the absence of a zip code will cause a long delay in a letter getting through?

And I'm wondering why I'm writing that first sentence in the present tense, like I'm being Damon Runyon...

- IanB