A related document on WWW is ``What to do when Tk says that your display
is insecure'',
http://ce-toolkit.crd.ge.com/tkxauth/. It was written by
Kevin Kenny. It suggests a similar solution to X authentication to that in
this document (xauth). However, Kevin aims more at using xdm to steer
xauth for you.
The X System Window System Vol. 8 X ``Window System Administrator's
Guide'' from
O'Reilly and Associates has also been brought to my attention as a good source of
information. Unfortunately, I've not been able to check it out.