XDR --
(programming)
External Data Representation,
provides an architecture-independent representation of data.
XDR language --
(programming)
A protocol specification language for data representation.
RPC language builds on and is a superset of XDR.
X Window System --
The network-based graphics windowing system developed at MIT
that is used as the foundation for many desktops.
X/Open --
X/Open®, X/Open Company Limited, a consortium of
computer firms dedicated to achieving open UNIX systems.
UNIX is a registered trademark in the USA and other countries,
licensed exclusively through X/Open Company, Ltd.