X Protocol
The X Window System Protocol, also known as X Window or X Protocol, is a graphics architecture used as the graphical system on UNIX systems (primarily) and Linux systems. The X Window System is also used, less commonly, on VMS, MVS, and MS-Windows systems. X Window System (X Protocol) provides an inherently client/server-oriented base for displaying windowed graphics. X Window provides a public protocol by which client programs can query and update information on X servers.
Standard Organization: X.org
X Window
The X Window System Protocol, also known as X Window or X Protocol, is a graphics architecture used as the graphical system on UNIX systems (primarily) and Linux systems. The X Window System is also used, less commonly, on VMS, MVS, and MS-Windows systems. X Window System (X Protocol) provides an inherently client/server-oriented base for displaying windowed graphics. X Window provides a public protocol by which client programs can query and update information on X servers.
Standard Organization: X.Org
X.121
X.121 is an ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between Public Data Networks (PDNs), connecting two network user addresses (NUAs). It consists of just fourteen digits and is sent over the Packet Layer Protocol (PLP) after the packet type identifier (PTI). IP addresses can be mapped to X.121 as described in RFC 1236.
Standard Organization: ITU-T
Reference Document: X.121
X.21
X.21 is an ITU-T standard for serial communications over synchronous digital lines. The X.21 protocol is used primarily in Europe and Japan.
Standard Organization: ITU-T
Reference Document: X.25
X.21bis
X.21bis is an ITU-T standard that defines the physical layer protocol for communication between DCE and DTE in an X.25 network.
Standard Organization: ITU-T
Reference Document: X.25
X.25
X.25, an ISO and ITU-T protocol for wide area network (WAN) communications, is a packet-switched data network protocol which defines the exchange of data as well as the control of information between a user device, called Data Terminal Equipment (DTE), and a network node, called Data Circuit Terminating Equipment (DCE). X.25 specifies LAPB, a data-link-layer protocol, and PLP, a network-layer protocol. Frame Relay has, to some degree, superseded X.25.
Standard Organization: ITU-T
Reference Document: X.25
X.28
X.28 is an ITU-T recommendation that defines the terminal-to-PAD interface in X.25 networks.
Standard Organization: ITU-T
Reference Document: X.25
X.29
X.29 is an ITU-T recommendation that defines the form for control information in the terminal-to-PAD interface used in X.25 networks.
Standard Organization: ITU-T
Reference Document: X.25
X.3
X.3 is an ITU-T recommendation that defines various PAD parameters used in X.25 networks.
Standard Organization: ITU-T
Reference Document: X.25
X.400
X.400 is the Message Handling Service protocol for email transmission specified by the ITU-T and ISO. X.400 is common in Europe and Canada and is an alternative to the more popular email protocol, Simple Mail Transfer Protocol (SMTP), which is defined by IETF. X.400 uses a binary format so it is easy to include binary contents without encoding it for transfer. Also, it is harder for people to fake email addresses and contents than with SMTP, where text messages are used.
Standard Organization: OSI / ITU-T
Reference Document: X.400
X.500
X.500, the directory Access Protocol by ITU-T (X.500) and also ISO (ISO/IEC 9594), is a standard way to develop an electronic directory of people in an organization so that it can be part of a global directory available to anyone in the world with Internet access.
Standard Organization: OSI / ITU-T
Reference Document: X.500
X.509
X.509 is an ITU-T standard for public key infrastructure (PKI). X.509 specifies, amongst other things, standard formats for public key certificates and a certification path validation algorithm. X.509 was initially issued in 1988 and was begun in association with the X.500 standard and assumed a strict hierarchical system of certificate authorities (CAs) for issuing the certificates. The X.500 system has never been fully implemented, and the IETF's public-key infrastructure working group has adapted the standard to the more flexible organization of the Internet. In fact, the term X.509 certificate usually refers to the IETF's PKI Certificate and CRL Profile of the X.509 v3 certificate standard, as specified in RFC 3280, commonly referred to as PKIX.
Standard Organization: ITU-T
Reference Document: X.509
X.75
X.75 is the signaling protocol for X.25, which defines the signaling system between two PDNs. X.75 is essentially an Network-to-Network Interface (NNI).
Standard Organization: ITU-T
Reference Document: X.75
X.86
X.86 is a physical interface sublayer (PHY) for 802.3 Ethernet Media Access Control (MAC) frames, which provides for the encapsulation of 802.3 MAC frames in a sublayer-level address and control frame, LAPS. X.86 allows 802.3 Ethernet switches and Hubs to interface directly with SDH (Recommendation G.707) transmission infrastructure for point-to-point data-link communications over Wide Area Networks (WANs). The data transfer rates for this new PHY reflect the various concatenated and non-concatenated payload rates in the SDH standard.
Standard Organization: ITU-T
Reference Document: X.86
X3T9.5: X Display Manager Control Protocol
X Display Manager Control Protocol (X3T9.5) isused to communicate between X terminals and workstations running the UNIX operating system.
Standard Organization: X.Org
XCAP: XML Configuration Access Protocol
Extensible Markup Language (XML) Configuration Access Protocol (XCAP) allows a client to read, write and modify application configuration data, stored in XML format on a server. XCAP maps XML document sub-trees and element attributes to HTTP URIs, so that these components can be directly accessed by HTTP. XCAP is a set of conventions for mapping XML documents and document components into HTTP URIs, rules for how the modification of one resource affects another, data validation constraints, and authorization policies associated with access to those resources.
Standard Organization: IETF
XDR: eXternal Data Representation
eXternal Data Representation(XDR) is a standard for the description and encoding of data. XDR is useful for transferring data between different computer architectures, and it has been used to communicate data between such diverse machines as the SUN WORKSTATION*, VAX*, IBM-PC*, and Cray*. XDR fits into the ISO presentation layer and is roughly analogous in purpose to X.409, ISO Abstract Syntax Notation. The major difference between these two is that XDR uses implicit typing, while X.409 uses explicit typing.
Standard Organization: IETF
Reference Document: RFC 4506
xDSL: Digital Subscriber Line
xDSL refers to a collection of Digital Subscriber Line(DSL) technologies, which is a modem technology for broadband data access over ordinary copper telephone lines (POTS) from homes to businesses. xDSL refers collectively to all types of DSL, such as ADSL (and G.Lite), HDSL, SDSL, IDSL and VDSL etc. They are sometimes referred to as last mile (or first mile) technologies because they are used only for connections from a telephone switching station to a home or office, not between switching stations.
Standard Organization: ANSI/ITU-T
Xerox IDP: Internet Datagram Protocol
Internet Datagram Protocol (IDP), a protocol in the Xerox protocol stack, is a simple, unreliable datagram protocol which is used to support the SOCK_DGRAM abstraction for the Internet Protocol (IP) family. IDP sockets are connectionless and normally used with the sendto and recvfrom subroutines. The connect subroutine can also be used to fix the destination for future packets, in which case the recv or read subroutine and the send or write subroutine can be used.
Standard Organization: Xerox
XGCP: eXternal Media Gateway Control Protocols
eXternal Media Gateway Control Protocols(XGCP) refers to a group of VOIP media gateway control protocols, including SGCP and MGCP.
XMPP: Extensible Messaging and Presence Protocol
Extensible Messaging and Presence Protocol (XMPP) is designed to stream XML elements for near-real-time messaging, presence, and request-response services. XMPP is based on the Jabber protocol, an open and popular protocol for instant messaging.
Standard Organization: IETF
Reference Document: RFC 3920
XML: Extensible Markup Language
Extensible Markup Language (XML), a subset of SGML, defines a syntax that lets you create markup languages to specify information structures. Information structures define the type of information, for example, subscriber name or address, not how the information looks (bold, italic, and so on). External processes can manipulate these information structures and publish them in a variety of formats. Text markup language designed to enable the use of SGML on the World Wide Web. XML allows you to define your own customized markup language. XML tags are not predefined. You must define your own tags. XML uses a Document Type Definition (DTD) or an XML Schema to describe the data. XML is not a replacement for HTML. Actually, XML and HTML are complimentary to each other.
Standard Organization: W3C
XMLDSIG: XML Digital Signatures
XML Digital Signatures (XMLDSIG) is a standard for creating and managing digital signatures using Extensible Markup Language (XML).
Standard Organization: IETF
Reference Document: RFC 3275
XKMS: XML Key Management Specification
XML Key Management Specification (XKMS) is a standard for encrypting information based on Extensible Markup Language (XML). XKMS comprises two services: the XML Key Information Service (X-KISS) and the XML Key Registration Service Specification (X-KRSS).
Standard Organization: W3C
XNS: Xerox Network System protocols
Xerox Network System (XNS) is a suite of protocols, providing routing capability and support for both sequenced and connectionless packet delivery. Many PC networking companies, such as 3Com, Banyan, Novell, and UB Networks used a variation of XNS as their primary transport protocol.
Standard Organization: Xerox
XON/XOFF
XON/XOFF is software data flow communications protocol for controlling the flow of data between computers and other devices. X stands for transmitter. XON/XOFF is frequently referred to as "software flow control". Typically, the receiver will send an XOFF character, when it can't take any more data (e.g. it may need time to process something), and when it can once again take more data, will send an XON character to the transmitter.
XOT: X.25 Over TCP
X.25 Over TCP(XOT) is developed by Cisco to transport X.25 over IP internets. The X.25 Packet Level requires a reliable link level below it and normally uses LAPB. XOT is a method of sending X.25 packets over IP internets by encapsulating the X.25 Packet Level in TCP packets.
Standard Organization: IETF
Reference Document: RFC 1613
Xmodem
XMODEM is a simple file transfer protocol in 1977 which became extremely popular in the early bulletin board system (BBS) market, largely because it was so simple to implement. It was also fairly inefficient, and as modem speeds increased this problem led to the development of a number of modified versions of XMODEM to improve performance or address other problems with the protocol. The later versions of XMODEM: YMODEN, especially the ZMODEN protocol developed based on the XMODEM had much better performance and replaced XMODEM in the early 1990s.