X

X Window System (X11)

Developed at MIT, a windowing system for Unix and similar hosts. Allows for multiple users, many different levels of customization, high flexibility, and reasonable overhead. Defined in RFC 1198.

X11

See the X Window System (X11).

X.25

An Open Systems Interconnection (OSI) protocol defining packet structure and exchange.

X.400

An Open Systems Interconnection (OSI) protocol (RFC 1465) defining mail exchange.

X.500

An Open Systems Interconnection (OSI) protocol (RFC 2120) defining directory services. See also Lightweight Directory Access Protocol (LDAP).

X/Open

An independent, worldwide, open systems organization headquartered in the UK and supported by most of the world's largest information system suppliers, user organizations and software companies. Its mission is to bring to users greater value from computing, through the practical implementation of open systems.

X pixmap (XPM)

An encoding standard for X Windows pixel maps. All Tivoli bitmaps (for example, icons) are stored in XPM format.

XDR

See eXternal Data Representation (XDR).

Xerox Network Systems (XNS)

The network architecture developed by the Xerox Corporation in the 1970s. The XNS Internet protocol suite is similar to the TCP/IP suite. However, different packet formats and terminology are used. XNS protocols establish a means of transport for data across an interconnection of network or Internet. A sample library provides user applications for XNS, such as the courier, associate printing, filing, and clearinghouse protocols.

XML

See eXtended Markup Language (XML).

XNS

See Xerox Network Systems (XNS).

XPG3

X/Open Portability Guide Version 3.

XPG4

X/Open Portability Guide Version 4.

XPM

See X pixmap (XPM).