Except that if you give me this URL, I get logged in as martin
(assuming I know your password). The FTPU scheme says "log in as
yourself". So you could have data readable by both martin and
eostrom, and point to it with the URL
<FTPU://genie.lut.ac.uk/whatever>
and both you and I could get at it without my having to know your
password or vice versa.