> Actually the spec has
> varied a bit over time, but both RFC 1630 describing WWW URLs and the
> latest standards-track URL definition from the URI WG declare that the
> tilde may not appear in URLs unencoded.
Given that HTTP is 8 bit clean, the only reason I can think of is people
passing URLs around in mail, through something awfull like an ASCII-EBCDIC
gateway. Is that it?