I hope I looked these up correctly, but here are the control
characters you have embedded in the listed URL.
%20 => <space>
%7C => |
%40 => @
%2F => /
If I remember correctly, the TIS http proxy filters out several
dangerous characters.......I think that %7C [pipe] is probably one of
them [possibly also %2F]. Read the http proxy source and I think you
will see where it is stripped out. I don't have the source available
right now, but glanced thru it several months ago looking for holes in
http and gopher.
Hope this helps you sort it out.