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X Display Manager control protocol (XDMCP)
A log-in feature that transparently establishes a connection between
the server (X station) and the host.
X protocol
A graphics description language that tells the X server within the
terminal how to draw the required objects on the screen.
X Series
Recommendations drawn up 51 by the ITU-TS to establish interfaces for
Terminal Equipment (DTE) and Data Circuit Terminating Equipment (DCE)
and public data networks (PDN).
X terminal
A dedicated terminal platform that is designed to run the X- server
software. It is used with machines that run 680 x 0 processors.
X Window System
An industry standard for graphical operating environments; it was
developed by the Massachusetts Institute of Technology (MIT) and
Digital Equipment. The system allows users simultaneously to run and
access applications in one or more host computers and display results
in multiple windows on one display screen.
X Window terminal
A diskless terminal with large local memory resources and some
intelligence.
X-on/X-off
A protocol that adjusts the flow of information for asynchronous serial
transmission.
X.1
International user classes of service.
X.110
International routing principles and routing plan for PDNs.
X.121
International numbering plan for PDNs.
X.130
Call set-up and clear-down times for international connection to
synchronous PDNs.
X.132
Grade of service over international connections to PDNs.
X.2
International data transmission services and optional facilities.
X.20
Asynchronous communications interface definitions for use over the
PSTN.
X.20 bis
V-series compatible modem, asynchronous communications interface
definitions for use over the PSTN.
X.21
The International Consultative Committee for Telephone and Telegraph
(CCITT) standard defining the interface between packet-type data
terminal equipment and a digital-interface unit.
X.21bis
A modification of the X.21 standard; it is identical to RS 232C at the
physical level.
X.24
An international interface specification established by the
International Consultative Committee for Telephone and Telegraph
(CCITT). It is closely compatible with the EIA standard, RS-232C.
X.25 1)
An International Consultative Committee for Telephone and Telegraph
(CCITT) standard that defines the interface between data terminal
equipment (DTE) and data circuit terminating equipment (DCE) for
workstations operating in packet switch mode across public data
networks. X.25 is used generically to describe packet-switching
networks, but this usage is misleading. The CCITT recommendation
defines the interface only; it does not specify how the network should
operate internally nor how it should be managed. X.25 is not a uniform,
constant standard; it has many variations, none of which is guaranteed
to operate with any other X.25 setup. X.25 has been a standard of the
CCITT since 1976. 2) A standard protocol suite for packet-switched
networks, approved by the (CCITT) and the International Organization
for Standardization (ISO). X.25 defines standard physical layer, link
layer and network layers (layers 1 through 3 of the open systems
interconnection model (OSI)). It was developed to describe how data
passes into and out of public data communications networks. X.25 is an
international narrowband (under 56Kbps) packet-switching standard. X.25
is a forerunner of frame relay and asynchronous transfer mode (ATM).
X.28
A data terminal equipment/data circuit terminating equipment (DTE/DCE)
interface for start-stop mode data terminal equipment accessing a
packet assembler-disassembler (PAD) in a public data network located
within a single country.
X.29
The International Consultative Committee for Telephone and Telegraph
(CCITT) standard for exchange of control information between a packet
assembler-disassembler (PAD) and a host.
X.3
Packet Assembly/Disassembly (pad).
X.3 T
The International Consultative Committee for Telephone and Telegraph
(CCITT) standard defining the packet assembler-disassembler (PAD).
X.30
Support of X.20 bis, X.21 and X.21 bis DTEs by ISDN.
X.31
Support of packet mode DTEs by ISDN.
X.32
Interface between DTE and DCE for terminals operating in packet mode
accessing public data networks via PSTN, ISDN or circuit switched PDN.
X.4
International Alphabet No.5 for character oriented data.
X.400
1) The International Consultative Committee for Telephone and Telegraph
(CCITT) standard for electronic mail exchange. 2) A store-and-forward
message handling system (MHS) standard that allows for the electronic
exchange of text and other electronic data such as graphics and fax
between different electronic mail systems.
X.400
Application Programming Interface Association (Xapia) Body
standardizing the interface to X.400 e-mail services. Other APIS, like
VIM and MAPI, are likely to comply with Xapia when it is finalized.
X.402
Overall Architecture.
X.403
Conformance Testing.
X.407
Abstract service definition conventions.
X.408
Encoded information type conversion rules.
X.411
Message transfer system.
X.413
Message store.
X.419
Protocol specifications.
X.420
Interpersonal messaging system.
X.50
Fundamental parameters of multiplexing scheme for the international
interface between synchronous data networks.
X.500
A directory services standard that permits applications such as
electronic mail to access a standard directory to enable global access
to users.
X.501
Models.
X.509
Authentication framework.
X.50bis
Fundamental parameters of 48Kbit/s transmission for the international
interface between synchronous data networks.
X.51
Fundamental parameters of multiplexing scheme for the international
interface between synchronous data networks using 10-bit envelope
structure.
X.511
Abstract service definition.
X.518
Procedures for distributed operation.
X.519
Protocol specifications.
X.51bis
Fundamental parameters of a 481Kbit/s transmission scheme for the
international interface between synchronous data networks using a
10-bit envelope structure.
X.520
Selected attribute types.
X.52
Selected object types.
X.58
Fundamental parameters of multiplexing scheme for the international
interface between synchronous data networks using a 10-bit envelope
structure.
X.60
Common channel signaling for circuit switched data applications.
X.61
Signaling system no.7 - data user part.
X.70
Terminal and transit control signaling for asynchronous services on
international circuits between anisochronous data networks.
X.71
Decentralized terminal and transit control signaling on international
circuits between synchronous data networks.
X.75
The International Consultative Committee for Telephone and Telegraph
(CCITT) recommendations for the interconnection and interoperation of
two packet switched public data networks which both support the X.25
user interface.
X.80
Interworking of inter-exchange signals for circuit switched data
services.
X.92
Hypothetical reference connections for synchronous PDNs.
X.96
Call progress signals in PDNs.
X.Windows
A networked GU I based on a client/server architecture, it displays
information from multiple networked hosts on a single workstation.
Available on PCs as X.terminal emulation and emulation on LAN servers.
X/Open
A body comprising of computer vendors, responsible for researching,
defining and publicizing open systems.
X3T9.5
The American National Standards Institute (ANSI) committee responsible
for defining the various specifications, including physical-layer
media-dependent (PMD), physical-layer protocol (PHY), media access
control (MAC), and station management (SMT), that comprise the
fiber-distributed data interface (FDDI) standard. See FDDI.
fiber-distributed data interface (FDDI)
Xapia
See X.400 Application Programming Interface Association (Xapia)
XDMCP
See X Display Manager control protocol (XDMCP)
Xerox networking system (XNS)
A mid-level International Organization for Standardization (ISO)
protocol used for Xerox local area networks (LANs).
XES
Output format for a Xerox high-speed printer.
XLR
A circular three-conductor shielded connector commonly used in
professional applications for connection of low-level balanced audio
signals to and from equipment.
XMISSION
See transmission
XMIT
See transmission
Xmodem
A popular public-domain program for transferring files through
asynchronous connections between personal computers. The Xmodem
protocol and functions have been incorporated into many other
communications products and are supported on other systems.
XNS
See Xerox networking system.
Xerox networking system (XNS)
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