UA UAE UART
UDP UKERNA UL
ULP UltraNet unbalanced configuration
Unbalanced Line UNI unicast UNINETT
unipolar UNISOURCE unity gain
UNIX UNMA unnumbered frames
UPS urban legend URC
URI URL URN
USART USENET
USENIX username UTC
UTP UUCP
UA (User Agent). An OSI
application process that represents a human user or organization in the
X.400 Message Handling System.
Creates, submits, and takes delivery of messages on the user's behalf.
UAE (Unrecoverable Applications
Error).
UART (Universal Asynchronous
Receiver/Transmitter). An integrated circuit incorporating a receiver/transmitter
that can convert parallel signals to the serial transmissions needed for
asynchronous communications.
UDP (User Datagram Protocol)
An Internet Standard transport layer protocol defined in STD
6, RFC
768. It is a connectionless protocol which adds a level of reliability
and multiplexing to IP. See also: connectionless,
Transmission Control Protocol. [Source:
RFC1392]
UKERNA
UK Education and Research Networking Association
UL (Underwriters Laboratories,
Inc.). Independent agency within thre United States that tests product
safety.
ULP (Upper-Layer Protocol).
A protocol higher in the OSI reference model than the current reference
point. ULP is often used to refer to the next-highest protocol in a particular
protocol stack.
UltraNet Very high-speed
(125 Mbps) network developed and marketed by Ultra Network Technologies.
unbalanced configuration HDLC
configuration with one primary station and multiple secondary stations.
Unbalanced Line A
transmission line in which a single conductor is used to transmit a signal
in reference to ground (for example in a coaxial cable).
UNI The user-network
interface defined by the ATM Forum for public and private ATM
network access. The interface between an ATM end system (such as a router)
and an ATM switch. Also used in Frame
Relay. Called SNI (Subscriber Network Interface) for SMDS.
UNI The user-network
interface defined by the ATM Forum for public and private ATM
network access. The interface between an ATM end system (such as a router)
and an ATM switch. Also used in Frame
Relay. Called SNI (Subscriber Network Interface) for SMDS.
unicast An address which
only one host will recognize. See also: broadcast,
multicast. Source: [RFC
1983]
unipolar Literally
meaning one polarity, unipolar is the foundamental electrical characteristics
of internal signals in digital communications equipment. Contrasted with
bipolar.
UNISOURCE
Loosely organised PNO alliance between CH, ES, NL, SE PNOs.
Unisource is the first truly pan-European telecom company, providing telecommunications
services to European corporations and individuals at work, on the move
or at home.
unity gain In broadband
networks, the balance between signal loss and signal gain through amplifiers.
UNIX A computer operating
system (the basic software running on a computer, underneath things like
word processors and spreadsheets). UNIX is designed to be used by many
people at the same time (it is "multi-user") and has TCP/IP built-in. It
is the most common operating system for servers on the Internet.
UNMA (Unified Network
Mangement Architecture). AT&T's network management architecture.
unnumbered frames HDLC
frames used for various housekeeping purposes, including link startup and
mode specification.
UPS (Uninterruptible Power
Supply).
Urban legend A story,
which may have started with a grain of truth, that has been embroidered
and retold until it has passed into the realm of myth. It is an interesting
phenomenon that these stories get spread so far, so fast and so often.
Urban legends never die, they just end up on the Internet! Some legends
that periodically make their rounds include "The Infamous Modem Tax," "Craig
Shergold/Brain Tumor/Get Well Cards," and "The $250 Cookie Recipe". [Source:
LAQUEY]
URC (Uniform Resource
Characteristic). URCs are a set of attribute/value pairs describing
an object. Some of the values may be URIs of various kinds, others may
include for example, authorship, publisher, data type, date, copyright
status and shoe size. URCs are not normally discussed as a short string,
but a set of fields and values with some defined free formatting. URC is
a mechanism of resource description, which can be seen as an instance of
the general problem of knowledge representation.
URI (Universal Resource
Identifiers). Is the name for a generic WWW identifier. The URI
specification simply defines the syntax for encoding arbitrary naming or
addressing schemes, and has a list of such schemes. The specification of
URIs as used by WWW
is to be distributed with informational status in the Internet community.
It is also published as RFC
1630.
URL (Uniform Resource
Locator), server and path information used to specify the location
of a document; URL is inserted in a document in the following format: scheme://host-domain[:port]/path/filename.
A URL looks like this:
../
or telnet://vax.cnuce.cnr.it
or ftp//ftp.cnr.it
etc.
The most common way to use a URL is to enter into a WWW browser program,
such as Netscape, or Lynx.
See also: Browser, WWW
URN (Uniform Resource
Name). To combat the transient nature of URLs, there are URNs. URNs
are defined to be permanent, globally unique names for resources. The main
idea with URNs is that the user can specify what is needed with a global
name, a specific file name (which can change every short while as explained
in the URL section above) is not necessary.
USART (Universal Synchronous/Asynchronous
receiver/Transmitter).
Usenet (NetNews). A collection
of thousands of topically named newsgroups, the computers which run the
protocols, and the people who read and submit Usenet news. Not all Internet
hosts subscribe to Usenet and not all Usenet hosts are on the Internet.
See also: Network News Transfer Protocol,
UNIX-to-UNIX CoPy. [Source: NWNET]
USENIX USENIX is the original
(soon to celebrate its 20th anniversary!) not-for-profit membership organization
of those individuals and institutions with an interest in UNIX, UNIX-related
and other modern operating systems and, by extension, in C++, X windows,
and other advanced computing technologies and tools The official name is
the UNIX and Advanced Computing Systems Professional and Technical Association,
but everybody just calls it USENIX. USENIX has their own WWW
page with additional information about USENIX.
username A unique "name"
by which each user is known to the system. This name is given to the user
whenever they register to use the system.
UTC (Universal Time Coordinated).
This is Greenwich Mean Time. [Source: MALAMUD]
UTP (Unshielded Twisted Pair).
General term for all local cabling systems used for transmission of data
which are not shielded.
UUCP (UNIX-to-UNIX CoPy).
This was initially a program run under the UNIX operating system that allowed
one UNIX system to send files to another UNIX system via dial-up phone
lines. Today, the term is more commonly used to describe the large international
network which uses the UUCP protocol to pass news and electronic mail.
See also: Electronic Mail, Usenet.
[Source: RFC1392].
Also: An international cooperative wide-area network of Unix computers
in the U.S., Europe, and Asia.
V. V.24 V.25bis dialing
V.28 V.42 V.42bis
VAN VAP
VADSL VBL VCCI
VCPI VDSL
vector VERONICA VESA
VFS VGA VIDC
VIM Virtual Circuit virtual route
Virus VIS VLIW
VLSI VLSM VME
VMS Voice Compression Voice Digitization
VPI/VCI VRAM
VRC VRML VSYNC
VTAM VTP VTS
VUCC
V. The ITU-TSS
V. standards describe data transfer via telephone lines.
V.24 A list of some
40 interface signals with usage and operational requirements. A given interface
complies with V.24 if its interface circuits are taken from the range of
V.24 interface circuits. As V.24 does not consider the electrical characteristics,
the type of connector and the pin assignment, V.24 is not an interface
definition, although often unproperly used as such.
V.25bis dialing A ITU-TSS
standard for in-band dialing on bit-synchronous (HDLC)
serial lines. Used in DDR. Supports
addresses call mode.
V.28 Is the definition of
the electrical characteristics of unbalanced interchange circuits. Significant
levels:
binary 0 has V >+3volts, binary 1 has V<-3volts.
Example: The interface RS-232-C
is compliant with V.24 and V.28.
V.42 A ITU-TSS
for Error protection through LAPM
and MNP4.
V.42bis A ITU-TSS
for Data compression using string tables.
VAN (Value-Added Network).
A communications network that provide such supplementary services as resources
management and message routing.
VAP (Value-Added Process).
VADSL (Very high speed
ADSL). Same as VDSL (or a subset of VDSL,
if VDSL includes symmetric mode transmission).[Source: ADSL
Forum]
VAT (Visual Audio Tool).
An X11-based audio teleconferencing tool. Vat allows users to conduct host-to-host
or multihost audio teleconferences over an internet (multihost conferences
require that the kernel support IP multicast). No special hardware other
than a microphone is required for vat - sound I/O is via a Sparcstation's
built-in audio hardware.
VBL (Vertical Blanking Interrupt).
VCCI (Voluntary Control
Council for Interference). Agency within Japan that deals with interference
generated by data-processing equipment.
VCPI (Virtual Control Program
Interface).
VDSL (Very high data rate
Digital Subscriber Line). Modem for twisted-pair access operating at data
rates from 12.9 to 52.8 Mbps with corresponding maximum reach ranging from
4500 feet to 1000 feet of 24 gauge twisted pair. [Source: ADSL
Forum]
vector A data segment
of an SNA message. A vector consists of a length field, a key that describes
the vector type, and vector specific data.
VERONICA (Very Easy
Rodent Oriented Net-wide Index to Computerized Archives) Was designed as
a solution to the problem of resource discovery in the rapidly-expanding
Gopher web, providing a keyword search of more than 500 Gopher menus. Veronica
helps you find Gopher-based information without doing a menu-by-menu, site-by-site
search. It is to the Gopher information space, what archie is to the FTP
archives.See also: Gopher [Source:
EARN Association]
VESA (Video Electronics
Standards Association)
VFS (Virtual File System)
VGA (Video Graphics Array).
A video adapter that allows monitors to display bit-mapped images with
256 variable colors at 640-by 480-pixel resolution.
VIC (Video Conference Tool).
An X11-based audio teleconferencing tool. Vat allows users to conduct host-to-host
or multihost audio teleconferences over an internet (multihost conferences
require that the kernel support IP multicast). No special hardware other
than a microphone is required for vat - sound I/O is via a Sparcstation's
built-in audio hardware.
VIDC (VIDeo Controller)
VIM (Vendor-Independent Messaging).
An API.
VINES (VIrtual NEtwork
System). A NOSdeveloped and marketed
by Banyan Systems.
Virtual Circuit A
network service which provides connection-oriented service regardless of
the underlying network structure. See also: connection-oriented.
[Source: RFC1392]
virtual route SNA terminology
for virtual circuit. A logical connection between subarea nodes that is
physically realized as a particular explicit route.
Virus A program which replicates
itself on computer systems by incorporating itself into other programs
which are shared among computer systems. See also: Trojan
Horse, worm. [Source: RFC1392]
VIS (Video Information System).
VLIW (Very Large Instruction
Word).
VLSI (Very Large-Scale Integration).
VLSM (Variable Length
Subnet Mask). The ability to specify a different subnets. VLSM can help
optimize available address space.
VME (Virtual Machine Environment).
VMS (Virtual Memory System).
The operating system for DEC's VAX.
Voice Compression The
conversion of an analog voice signal into a digital signal using minimum
bandwidth (16 Mbps or less).
Voice Digitization (Voice
Encoding). The conversion of an analog voice signal into digital symbols
for storage or for transmission (examples ADPCM, CVSD, or PCM)
VPI/VCI (Virtual Path
Identifier/Virtual Channel Identifier). Combined, these fields identify
aconnection in the ATM network. VCI uses
16 bits and VPI uses 8 bits.
VRAM (Video RAM). Memory
required for high-speed video applications.
VRC (Vertical Redundancy
Check).
VRML (Virtual Reality Modeling
Language). A language for describing multi-participant interactive simulations
-- virtual worlds networked via the global Internet and hyperlinked with
the World Wide Web. All aspects of virtual world display, interaction and
internetworking can be specified using VRML. It is the intention of its
designers that VRML become the standard language for interactive simulation
within the World Wide Web. See: The VRML
Forum
VSYNC (Vertical SYNchronization).
VTAM (Virtual Telecommunications
Access Method). A set of programs that control communication between nodes
and application programs running on a host system.
VTP (Virtual Terminal
Protocol). An ISO application for establishing
a virtual terminal connection across a network.
VTS (Virtual Terminal
Service) OSI/Application Layer
VUCC
Vienna University Computer Center. (Vienna University is the
biggest Austrian university). In addition to caring for the local networking
setup, VUCC is tasked with operations and maintenance of ACOnet,
as well as with the operations of the Ebone
node in Vienna (a.k.a. Vienna-EBS) and
a sizable set of international links to central and eastern Europe (Poland,
Czechia, Slovakia, Hungary, Romania, Bulgaria, Croatia, Slovenia, Macedonia
(FYROM))
WAIS WAN waveform coding
Western jack WG WHOIS
White Pages Wide Area Information Servers Wide Area Network
wideband WIMP WINS
wiring closet
WISC World Wide Web (WWW or W3) workstation
WORM WOSA WRT
WYSCNET WYSIWYG
WAIS (Wide Area Information
Servers). A distributed information service which offers simple natural
language input, indexed searching for fast retrieval, and a "relevance
feedback" mechanism which allows the results of initial searches to influence
future searches. Public domain implementations are available. See also:
Archie, Gopher,
Prospero. [Source: RFC1392]
WAN (Wide Area Network).
A network, usually constructed with serial lines, which covers a large
geographic area. See also: Local Area Network,
Metropolitan Area Network. [Source:
RFC1392]
waveform coding Electrical
techniques used to convey binary signals.
Web Another name of
World Wide Web
Western jack Telephone
wall outlet connector used in the U.S. and other countries.
WG (Working Group).
WHOIS An Internet program
which allows users to query a database of people and other Internet entities,
such as domains, networks, and hosts, kept at the DDN NIC. The information
for people shows a person's company name, address, phone number and email
address. See also: Defense Data Network Network
..., white pages, Knowbot,
X.500. [Source: FYI4]
White Pages The Internet
supports several databases that contain basic information about users,
such as email addresses, telephone numbers, and postal addresses. These
databases can be searched to get information about particular individuals.
Because they serve a function akin to the telephone book, these databases
are often referred to as "white pages. See also: Knowbot,
WHOIS, X.500.
[Source: RFC1392]
wideband See broadband
WIMP (Windows, Icons, Menus,
and Pointing device).
WINS (Windows Internetworking
Name Server). The Windows NT implementation of NBNS
is called WINS. They were called Rhino servers (this was the code name
of the project in Microsoft for NBT implementation). This name was kept
as the name of one of the Microsoft Internet servers for NT - rhino.microsoft.com,
recently renamed to internet.microsoft.com.
wiring closet Specially
designed room used for wiring data and voice networks. Wiring closets serve
as a central junction point for wiring and wiring equipment that is used
for interconnecting devices.
WISC (Writable Instruction
Set Computer).
World Wide Web (WWW or W3
or Web) A Hypertext-based, distributed
information system created by researchers at CERN
in Switzerland. Users may create, edit or browse Hypertext documents. The
clients and servers are freely available. [Source: RFC1392]
workstation A networked
personal computing device with more power than a standard IBM PC or Macintosh.
Typically, a workstation has an operating system such as unix that is capable
of running several tasks at the same time. It has several megabytes of
memory and a large, high-resolution display. Examples are Sun workstations
and Digital DEC stations. [Source: ZEN ]
WORM A computer program
which replicates itself and is self-propagating. Worms, as opposed to viruses,
are meant to spawn in network environments. Network worms were first defined
by Shoch & Hupp of Xerox in ACM Communications (March 1982). The Internet
worm of November 1988 is perhaps the most famous; it successfully propagated
itself on over 6,000 systems across the Internet. See also: Trojan
Horse, virus.
Also (Write One, Read Many times).
WOSA (Windows Open Services
Architecture).
WRT (With Respect To).
WISCNET TCP/IP network
in Wisconsin, U.S.A. connecting 27 campuses of the University of Winsconsin
plus a number of private lolleges. Links are 56 Kbps and T1.
WYSIWYG (What You See
is What You Get).
X XA XAPIA
XCMD XModem XMS
XON/XOFF XOR X Recommendations
X. X/Open X.21
X.25 X.28 X.29
X.3 X.3T9.5 X.400
X.500 XBM XDMCP
XDR Xerox Network System XI
XID Xid XLINK
XNS XTP XRemote
X Windows
X Is the name for TCP/IP
based network-oriented window systems. Network window systems allow a program
to use a display on a different computer. The most widely-implemented window
system is X11 - a X/Open component of MIT's Project Athena.
XA (eXtended Architecture).
XAPIA (X.400
API Association).
XCMD (eXternal CoMmanD).
A user defined command that uses built-in Macintosh code to extend the
features of HyperCard.
XModem A widely used,
though somewhat aged , file transfer protocol. The use of 128 byte data
blocks severely limits the achievable throughput.
XMS (eXtended Memory Specification).
A set of rules defining a software interface that provides DOS applications
with access to extended memory.
XON/XOFF (Transmitter
On/ Transmitter Off). Control character used for flow control, instructing
a terminal to start transmission (X-ON) and end transmission X-OFF).
XOR (eXclusive-OR).
X Recommendations The
CCITT/ITU
documents that describe data communication network standards. Well-known
ones include: X.25 Packet Switching
standard, X.400 Message Handling
System, and X.500 Directory X
Services.
X. The ITU-TSS
X. standards describe data transfer in public data network.
X/Open A group of computer
manufacturers that promotes the development of portable applications based
on UNIX. They publish a document called the X/Open Portability Guide.
X.21 Is an interface
definition by CCITT/ITU
for synchronous operation between a Data Terminal equipment (DTE)
and a Data Circuit-terminating Equipment (DCE)
on a public data network. The electrical characteristics comply with X.27
(V.11), while the mechanical arrangements comply with ISO4903 (15-pole
connector).
X.25 A data communications
interface specification developed to describe how data passes into and
out of public data communications networks. The CCITT
and ISO approved protocol suite defines
protocol layers 1 through 3. [Source: RFC1392]
X.28 A CCITT recommendation
that defines the terminal-PAD interface.
X.29 A CCITT recommenadtoion
that defines the PAD-computer terface.
X.3 A CCITT recommendation
that defines various PAD parameters.
X3T9.5 The number assigned
to the Task Group of Accredited Standards Commettee for their internal,
working document describing the Fiber Distributed Data Interface. See FDDI.
X.400 The CCITT and
ISO standard for electronic mail. It is widely used in Europe and Canada.
[Source: RFC1392]
X.500 The CCITT and ISO
standard for electronic directory services. See also: white
pages, knowbot, WHOIS.
[Source: RFC1392]
XBM X BitMap, a black-and-white
image format
XDMCP X Display Manager
Control Protocol. Protocol used to communicate between X terminals and
workstations running UNIX.
XDR (eXternal Data Representation)
A standard for machine independent data structures developed
by Sun Microsystems and defined in http://www.cis.ohio-state.edu/htbin/rfc/rfc1832.html>RFC
1832. It is similar to ASN.1. See also: Abstract
Syntax Notation One. [Source: RFC1208]
XI X.25 SNA Interconnect.
OSI/SNA - IBM software for 37XX controllers with NCP provides DCE interface
to X.25 compatible computers.
XID Exchange identification.
Xid See termid
XLINK
(eXtended Local Informatics Network Karlsruhe). A German ISP.
XTP (Xpress Transport
Protocol). The XTP is a transport layer protocol designed to provide
a wide range of communication services built on the concept that orthogonal
protocol mechanisms can be combined to produce appropriate paradigms within
the same basic framework.
Follow the XTP Forum
link to find out more about research and products related to XTP
XNS (Xerox Network System) A
network developed by Xerox corporation. Implementations exist for both
4.3BSD derived systems, as well as the Xerox Star computers. [Source: RFC1392]
XRemote Protocol developed
specifically to optimize support for X Windws over a serial communications
link.
X Windows Distributed,
network-transparent, device-independent, multitasking windowing and graphics
system originally developed by MIT for communication between X terminals
and UNIX workstations.
YP YModem
YP (Yellow Pages). A service
used by UNIX administrators to manage databases distributed across a network.
[Source: RFC1392].
YModem File transfer protocol
wich uses data blocks of 1 Kbytee and transfers filenames and more than
one file in one transfer.
zero suppression ZIF ZIP
ZModem zone
zero code suppression Coding
scheme to substitute a one in the seventh bit of a string of eight consecutive
zeros. See also pulse density.
ZIF (Zero Insertion Force).
ZIP (Zig-zag In-line Package/pin).
ZModem A file transfer
prtotocol with variable block size, reinitiation of aborted transfer of
several files in one trnasfer along with file (and path) names.
zone In Apple
Talk, a logical group of network devices.