How to get an X server system to send XDMCP?

[Julian Elischer]

I need to make an X server act as an X-terminal
and run the chooser, offering up a set of 
systems to log into at initial powerup.

I am sure I have done this before but I'll be damned if I can see
from teh current docs how to do this again..

I can make the other end.. a system that offers xdm service..
without too much problem, but I can't see how to make an xdm 
start teh X server and then get that xdm on the far system to 
offer service, put up a menu of systems (the chooser) and then 
select one of them as the base login system.

Julian

(Who has managed to do this before but can't remember how)