This article is from the Douglas Adams FAQ, by Nathan Hughes email@example.com with numerous contributions by others.
You can find this (lengthy) discussion at my ftp site at ftp.umd.umich.edu
in people/nhughes/hhg/diff.us.uk. I decided to take it out of the FAQ
to conserve space (and bandwidth), but will put it back if I'm requested
to. It's also available on the IHG at