XWINDOWS question

[R.TRAUBEN]

Hello:

Does anyone have a pointer in the public domain literature to 
a program called XWINDOWS? 

It is a portable bitmapped window manager developed at MIT which
runs under Berkeley UNIX.

I would like to find out more about its capabilities and whether 
its functionality is similar to the ATT DMD 5620 layers software.
Can it run under UNIX 5.2 or greater? How similar is it to the DGIS 
window management software? 

Does it subsume CGI/VDI software while doing window management 
or does it make assumptions about some underlying CGI/VDI functions.

Does any 3rd party software house port XWINDOWS? (As GSS and others
do for DGIS). 

I am interested in any experiences others may have had with
such firms and wonder whether they would use XWINDOWS again
if they had the choice.

Richard