Xdmx is a proxy X server that uses one or more other X servers
as its display devices. It provides multi-head X functionality
for displays that might be located on different machines.
Xdmx functions as a front-end X server that acts as a proxy
to a set of back-end X servers. All of the visible rendering is
passed to the back-end X servers. Clients connect to the Xdmx
front-end, and everything appears as it would in a regular
multi-head configuration. If Xinerama is enabled (e.g.,
with +xinerama on the command line), the clients see a single large screen.

Xdmx communicates to the back-end X servers using the standard X11 protocol,
and standard and/or commonly available X server extensions.