Auto Answer
A modem indicator light that tells you the modem is ready to pick up the phone, so long as there's a communication program running and prepared to handle the call. The light is often not shining even when the modem is prepared to take a call, so it's not a useful light.

ATM Adapation Layer
The standards layer that allows multiple applications to have data converted to and from the ATM cell. A protocol used that translates higher layer services into the size and format of an ATM cell.

AAL
Connection Association established by the AAL between two or more next higher layer entities.

AAL-1
ATM Adaptation Layer Type 1: AAL functions in support of constant bit rate, time-dependent traffic such as voice and video.

AAL-2
ATM Adaptation Layer Type 2: This AAL is still undefined by the International Standards bodies. It is a placeholder for variable bit rate video transmission.

AAL-3/4
ATM Adaptation Layer Type 3/4: AAL functions in support of variable bit rate, delay-tolerant data traffic requiring some sequencing and/or error detection support. Originally two AAL types, i.e. connection-oriented and connectionless, which have been combined.

AAL-5
ATM Adaptation Layer Type 5: AAL functions in support of variable bit rate, delay-tolerant connection-oriented data traffic requiring minimal sequencing or error detection support.

AAP
The Association of American Publishers: engaged in standardisation efforts in document preparation.

AAP DTD
A DTD for a standard SGML document type for scientific documents, defined by the AAP

ABI
Application Binary Interface: the interface by which an application program gains access to operating system and other services, designed to permit porting of compiled binary applications between systems with the same ABI.

ABR Available Bit Rate:
ABR is an ATM layer service category for which the limiting ATM layer transfer characteristics provided by the network may change subsequent to connection establishment. A flow control mechanism is specified which supports several types of feedback to control the source rate in response to changing ATM layer transfer characteristics. It is expected that an end-system that adapts its traffic in accordance with the feedback will experience a low cell loss ratio and obtain a fair share of the available bandwidth according to a network specific allocation policy. Cell delay variation is not controlled in this service, although admitted cells are not delayed unnecessarily.

Absolute pathname
A pathname that tells you how to find a file by starting at the root directory and working down the directory tree.

Abstract Class
In object-oriented programming, a class designed only as a parent from which sub-classes may be derived, but which is not itself suitable for instantiation. Often used to "abstract out" incomplete sets of features, which may then be shared by a group of sibling sub-classes, which add different variations of the missing pieces.

Abstract Syntax Notation One (ASN.1)
The OSI language for describing abstract syntax, which is a description of data structures independent of machine orientation.

Abstract Syntax Representation, revision #I (ASN.I)
A description of a data structure that is independent of machine-oriented structures and encodings.

ACA
Application Control Architecture: DEC's implementation of ORB

Access Control List (ACL)
Defines the roles that are required to execute a method. Defines the user or group IDs of people who do (or do not) have
explicit access to a file or directory.

AC-3 (Dolby Digital)
This digital surround-sound format for home audio is called Dolby Digital in theaters. It is a 5.1 format, with six separate audio tracks. AC-3 has been chosen as the official sound format for digital TV, and is already encoded on many DVDs and Laserdiscs.

ACCOUNT
An e-mail account is the arrangement you've made with an ISP or network administrator in which space is allocated on a server for your mail, and in which you're assigned the right to send and received e-mail.ACE Advanced Computing Environment: a consortium to agree on an open architecture based on the MIPS R4000 chip. A computer architecture ARCS will be defined, on which either OS/2 or Open Desktop can be run.

ACE
Adaptive Communication Environment, a C++ Wrapper Library for communications from the University of California at Irvine.

ACK (acknowledgement )
When a modem receives a data packet, it sends a signal back to the sending modem. If all the data is present and correct, it sends an ACK (acknowledgement) signal, which acts as a request for the next data packet. If the modem didn't get all the data, it sends back a negative acknowledgement, or NAK.

ACL
Agent Communication Language.

ACL
Asynchronous Connectionless Link, type of data packet (data only).

ACL
Access Control List.ACM Association for Computing Machinery.

ACM Address Complete Message:
A BISUP call control message from the receiving exchange to sending exchange indicating the completion of address information.

ACPI Advanced Configuration and Power Interface
This power management standard, proposed by Microsoft, Intel, and Toshiba, lets the PC control power to peripherals like CD-ROMs and printers, as well as consumer devices hooked up to the PC. Peripherals can also use ACPI to turn on the PC. For example: you could insert a CD-ROM into a drive, and the computer would automatically boot up.

ACR Attenuation to Crosstalk Ratio:
One of the factors that limits the distance a signal may be sent through a given media. ACR is the ratio of the power of the received signal, attenuated by the media, over the power of the NEXT crosstalk from the local transmitter, usually expressed in decibels (db). To achieve a desired bit error rate, the received signal power must usually be several times larger than the NEXT power or plus several db. Increasing a marginal ACR may decrease the bit error rate.

ACR Allowed Cell Rate:
An ABR service parameter, ACR is the current rate in cells/sec at which a source is allowed to send.

Acrobat
A platform-independent text and image formatter/viewer from Adobe Systems.

Actis
An approach to integrated CASE by Apollo.

Active Channels
An Active Channel is what Microsoft calls a Web site that has been enabled for push delivery to Internet Explorer 4.0 browsers. To create a channel, developers write and upload a CDF (channel definition format) file to their Web site; new content is delivered to users automatically when the site is updated. Developers and subscribers can control the update frequency; which channels, subchannels, and items (sections) are subscribed to; and other channel characteristics. Most Active Channels use dynamic HTML (DHTML) and other effects to spice up content and make it more interactive.

Active Matrix
Flat-panel displays for laptop computers are created by laying diodes over a superfine grid of wires. The diodes are activated by applying current to various points around the grid. Connect enough of these dots and you get an image. Active-matrix displays use transistors to keep their diodes in an on or off state, unlike their passive-matrix cousins, which rely on the diodes' persistence. As a result, active-matrix displays are brighter and produce better color than passive-matrix displays. However, the additional technology required to build active displays also makes them far more expensive.

Active object
An object that encompasses its own thread of control.

Active DBMS
A conventional or passive DBMS combined with a means of event detection and condition monitoring. Event handling is often rule-based, as with an expert system.ActiveX A software development kit from Microsoft for development of Internet applications and content.

ACTIVEX
A new programming standard proposed by Microsoft Corporation which would increase the functionality of webpages. Similar in nature to Java and Javascripts.

Active timing
This is defined as the portion of the Video Signal that carries the actual Video information. Surrounding this region, is the front porch and back porch.Actor In object-oriented programming, an object which exists as a concurrent process.

Actor
A term in Chorus denoting the unit of resource allocation.

Actra
A multiprocessor Smalltalk project.

Actual Image Size
The size of the display on the screen is dependent upon the timing signals provided by the video card. The displayable diagonal linear measurement can vary based on the graphic mode being generated and how the monitor responds to the characteristics of the signal.

AD/Cycle (AD = Application Development):
a set of SAA-compatible IBM-sponsored products for program development, running on workstations accessing a central repository on a mainframe. The stages cover requirements, analysis and design, production of the application, building and testing, and maintenance. Technologies used include code generators and knowledge based systems, as well as languages and debuggers.

Ada
A high-level computer language sponsored by the US Department of Defense. It has a multitasking mechanism, and a number of features useful for software engineering.

AdaIC
Ada Information Clearinghouse

Adaline
Name given by Widrow to ADAptive LInear NEurons, that is neurons (seeMcCulloch-Pitts), which learn using the Widrow-Huff Delta Rule (see also Madaline).

ADAMO
A data management system written at CERN based on the Entity-Relationship model.

Adaptable User Interface
A toolkit from Oracle allowing applications to be written portably for different windowing systems. It provides one call level interface along with a resource manager and editor across a range of "standard" GUIs, including Macintosh, Windows and the X Window System.

Adaptive Differential Pulse Code Modulation (ADPCM)
A way to reduce the bandwidth needed by digitized voice channels by half (to 32 Kb from 64 Kb).

Adaptive learning
Learning in which a system programs itself by adjusting weights or strengths until it produces the desired output. Same as Hebbian

ADDD
A Depository of Development Documents. A public domain Software Engineering Environment from GMD developed as part of the STONE project.

Address
In TCP/IP, an IP address is a 32-bit numeric identifier assigned to a node. The address has two parts, one for the network identifier and the other for the node identifier. All nodes on the same network must share the network address and have unique node address. For networks connected to the Internet, network addresses are assigned by the Internet Activities Board (IAB).
Addresses also include IPX addresses -the internal network number and external network number-and the MAC (Media access Control) address assigned to each network card or device.

Address
The name you use to say who is supposed to receive an electronic-mail message. An electronic-mail address consists of the person's user name and , if the person is on a different computer than you are, the name of the computer.

ADDRESS BOOK
An address book is a file in which you can store the e-mail addresses of people to whom you frequently write. When you add a person to your address book, you'll typically enter the person's real name and his or her e-mail address. In some e-mail programs, as you type the person's real name in the recipient field of a new message, the program will automatically locate the person's real name and e-mail address and fill it in for you.

Address Prefix
A string of 0 or more bits up to a maximum of 152 bits that is the lead portion of one or more ATM addresses.

Address Resolution
Address Resolution is the procedure by which a client associates a LAN destination with the ATM address of another client or the BUS.

Address Resolution Protocol (ARP)
An Ethernet protocol used to translate IP network addresses into Ethernet hardware addresses (also known as Media Access Control (MAC) addresses).

Adjacency
The relationship between two communicating neighboring peer nodes.

Adjacent hosts
Two hosts are adjacent if they have permanent ARP entries for each other.

ADL
Assertion (or API) Definition Language. A project for Automatic Interface Test Generation.

Administrator
In the context of Tivoli, a user who is authorized to perform some TME function. See also system administrator.

Administrative Domain
A collection of managed entities grouped for administrative reasons.

ADO ActiveX Data Objects
A Microsoft technology that provides a unified way to access different data sources with a single data model. By providing a single data model, ADO lets you access data in the same way whether it exists in a database, a spreadsheet, and even text files.

ADPCM
Adaptive Differential Pulse Code Modulation: A reduced bit rate variant of PCM audio encoding (see also PCM). This algorithm encodes the difference between an actual audio sample amplitude and a predicted amplitude and adapts the resolution based on recent differential values.

ADT
Abstract Data Type: a class of data structures described by means of a set of operations rather than by physical representation, such as a class in object-oriented programming..

ADTF
ACR Decrease Time Factor: This is the time permitted between sending RM-cells before the rate is decreased to ICR (Initial Cell Rate). The ADTF range is .01 to 10.23 sec. with granularity of 10 ms.

Advanced Development Environment (ADE)
A toolkit for programmers to use in developing systems management applications in the TME. This requires knowledge of how the underlying object system works.

Advance Research Projects Agency Network (ARPANET)
A packet-switched network developed in the early 1970s. The “father” of today’s Internet. ARPANET was decommissioned in June 1990.

Advanced Technology Adapter (ATA)
Another name for Integrated Disk Electronics (IDE).

Aegis
A CASE tool for project change management, part of the GNU software.

AENOR
Asociacion Espanola de Normalizacion y Certificacion. The Spanish standards organisation.

AEP
Application environment profile.

AES
Application environment specification: a set of specifications from OSF for programming and user interfaces, aimed at providing a consistent application environment on different hardware platforms. It includes O/S for the operating system (user commands and program interfaces), U/E for the User Environment (Motif), and N/S for Network services.

AFI
Authority and Format Identifier: This identifier is part of the network level address header.

AFIPS
American Federation of Information Processing Societies.

AFNOR
Association Francaise pour la Normalisation: the French national standards institute, a member of ISO.

Aggregation
Token A number assigned to an outside link by the border nodes at the ends of the outside link. The same number is associated with all uplinks and induced uplinks associated with the outside link. In the parent and all higher-level peer group, all uplinks with the same aggregation token are aggregated.

Agent
A piece of software running autonmously, usually helping a human being in pursuit of some knowledge-related goal.

AGOCG
Advisory Group on Computer Graphics. Advising UK Higher Education on Computer Graphics, Visualization and Multimedia.

AGL
Atelier de Genie Logiciel: French for IPSE.

Agents
In the client/server model, the part of the system that performs information preparation and exchange on behalf of a client or server application.

AHFG
ATM-attached Host Functional Group: The group of functions performed by an ATM-attached host that is participating in the MPOA service.

AI
Artificial Intelligence.
Ai
Signaling ID assigned by Exchange A.

AIA
Application Integration Architecture: DEC's "open standards" specifications.

AICA
Associazione Italiana di Calcolo Automatico.

AIFF
Audio IFF. A format developed by Apple for storing high-quality sampled sound and musical instrument info; also used by SGI and several professional audio packages.

AIM
ATM Inverse Multiplexer: A term discontinued because of conflict with an established product. Refer to AIMUX.

AIMUX
ATM Inverse Multiplexing: A device that allows multiple T1 or E1 communications facilities to be combined into a single broadband facility for the transmission of ATM cells.

AIR
Additive Increase Rate: An ABR service parameter, AIR controls the rate at which the cell transmission rate increases. It is signaled as AIRF, where AIRF = AIR*Nrm/PCR.

AIRF
Additive Increase Rate Factor: Refer to AIR.

AIS
Alarm Indication Signal: An all ones signal sent down or up stream by a device when it detects an error condition or receives an error condition or receives an error notification from another unit in the transmission path.

AIS
Advanced Informatics Support project for administrative work at CERN.

AIX
Advanced Interactive eXecutive: IBM's version of UNIX, taken as the basis for the OSF standard.

Algol
A high-level programming language developed in the 1950s.

Algorithm
A systematic procedure guaranteed to produce a result after a finite number of steps.

Alias
A pointer to one or more users or hosts, typically used for sending mail (in the case of users) or logging in remotely (in the case of hosts). See also group alias, host alias, individual alias.

Alt key
If your keyboard has an alt key, it is used as a shift key; it does nothing on its own. To use it, hold it down, press another key, and release it. To press alt-A, for example, hold the Alt key, press and release the A key, and release the Alt key.simple.

Alternate Routing
A mechanism that supports the use of a new path after an attempt to set up a connection along a previously selected path fails.

Alvey
A funding programme for collaborative research in the UK.

AMADEUS
A PC client for Hyper-G.

American National Standards Institute (ANSI)
The organization responsible for setting computer-related standards in the United States of America.

American National Standards Institute (ASNI)
A nonprofit organization responsible for the ASCII (American Standard Code for Information Interchange) code set, as well as numerous other voluntary standards.

American Standard Code for Information Interchange (ASCII)
The character set used by most American computers. Supersets of ASCII contain non-English characters.

AMI
Alternate Mark Inversion: A line coding format used on T1 facilities that transmits ones by alternate positive and negative pulses.

Ami
Applications of Metrics in Industry (Assess, Analyze, Metricate, Improve). A method for software project management and process improvement.

Amoeba
A distributed operating system developed by A.Tanenbaum and others at Amsterdam.

AMS
Andrew Message System.

Analysis
The part of the software development process concerned with defining the requirements for the product.

Ancestor Node
A logical group node that has a direct parent relationship to a given node (i.e., it is the parent of that node, or the parent's parent, ...).

ANDF
Architecture-Neutral Distribution Format: an emerging OSF standard for software distribution. Programs are compiled into ANDF before distribution, and executables are produced from it for the local target system.

Andrew File System (AFS)
A specific instance of a distributed file system (DFS), developed at Carnegie-Mellon University (CMU), allowing multiple file systems to be shared between organizations and treated, at the user interface level, as one giant file system.

Andrew File System
The distributed file system of the Andrew project, adopted by the OSF as part of their DCE.

Andrew Message System
A multimedia interface to electronic mail and bulletin boards, developed as part of the Andrew project

Andrew Project
A distributed system project for support of educational and research computing at Carnegie Mellon University.

Andrew Toolkit
A portable user interface toolkit developed as part of the Andrew project, running on the X Window System and distributed with X11R5.

ANI
Automatic Number Identification: A charge number parameter that is normally included in the Initial Address Message to the succeeding carrier for billing purposes.

ANL
Argonne National Laboratory, USA.

ANM
Answer Message: A BISUP call control message from the receiving exchange to the sending exchange indicating answer and that a through connection should be completed in both directions.

Anna
A specification language from Stanford University for formally specifying Ada programs. It has a Specification Analyzer and a Consistency Checking System.

Annealing
A technique which can be applied to any minimization or learning process based on successive update steps (either random or deterministic) where the update step length is proportional to an arbitrarily set parameter which can play the role of a temperature. Then, in analogy with the annealing of metals, the temperature is made high in the early stages of the process for faster minimization or learning, then is reduced for greater stability.

Anonymous ftp
Uses the ftp file transfer program and the internet to copy files from other computers to your own. It is anonymous because many computer systems allow anyone to log in and transfer files without having accounts(usernames) on the computer. You type anonymous as the user name and electronic-mail address as the password.

ANSA
Advanced Network Systems Architecture: an architecture for distributed computer systems based on a model developed as an Esprit project - .

ANSI
American National Standards Institute: A U.S. standards body.

ANSI Z39.50 See Z39.50.

ANSI/SPARC Architecture
A layered model of database architecture comprising a physical schema, a conceptual schema, and user views.

AnswerGarden
A help desk software package from MIT.

Anycast
A one packet to one from a list of hosts; similar to a broadcast or multicast but the goal is to have exactly one response. See also broadcast, multicast, unicast.

AOCE
Apple Open Collaboration Environment. A set of software for e-mail, directory services etc.

APA
Application Portability Architecture: DEC's plan for portable applications software.

apE
A graphics package from the Ohio Supercomputer Centre .

Apertos
An object-oriented operating system from Sony Computer Science Laboratory.

API
Application Program Interface: API is a programmatic interface used for interprogram communications or for interfacing between protocol layers.

API_connection
Native ATM Application Program Interface Connection: API_connection is a relationship between an API_endpoint and other ATM devices that has the following characteristics:
· Data communication may occur between the API_endpoint and the other ATM devices comprising the API_connection
· Each API_connection may occur over a duration of time only once; the same set of communicating ATM devices may form a new connection after a prior connection is released
· The API_connection may be presently active (able to transfer data), or merely anticipated for the future

APL
A Programming Language developed by Iverson for mathematical applications.

Apollo
Apollo Computer, now a division of Hewlett-Packard, also the name of a range of workstations manufactured by this company.

AppKit
A set of objects used by the application builder for the NeXTstep environment.

Apple
Apple Computer Inc, manufacturers of the Macintosh range of Personal Computers.

Appletalk
The proprietary local area network protocol developed by Apple for their Macintosh range of processors. Current implementations exist on Localtalk and Ethertalk.

AppleTalk Address Resolution Protocol (AARP)
Provides for the dynamic assignment of node identifiers to nodes within an AppleTalk network.

Applet
A small application, often downloaded from a remote server and run in a controlled environment. Typically written in a language such as Java for execution by a WWW browser.

applet
A Java program that is designed to be embedded in a Web page.

APPLET
The name given to a small binary file which is executed on your computer as part of a Web Page loading. Applets are created by JAVA. Applets should not be confused with pages which have JAVASCRIPT in them.

Application
A program that really gets some work done. Some programs just organize the computer, get its parts talking to each other, and do other housekeeping chores. Application programs do real-world work, like word processing or accounting.

Application Layer
The layer of the OSI model that interfaces with user mode applications by providing high-level network services based upon lower-level network layers. Network file systems like named pipes are an example of Application layer software. See Named Pipes, Open Systems Interconnection.

Application Programmer Interface (API)
A programming specification that allows an application programmer to interface to an application or suite of applications.

Application Program Interface (API)
A Set of routines that an application program uses to request and carry out lower-layer services performed by the operation system.

Application Extension Facility (AEF)
A tool kit for systems administrators to use in customizing a TME application to specific needs. This does not require any knowledge of how the underlying object system works.

APPN
Advanced Peer to Peer Network: IBM network architecture for building dynamic routing across arbitrary network topologies. Intended as an eventual replacement for SNA, IBM's static routed, hierarchical network architecture.

APSE
Ada Programming Support Environment.

ARC
(Previously ARCS) Advanced RISC Computing Specification: the standard hardware architecture of ACE., specifying the baseline hardware requirements to create ACE-compatible systems.

Arcadia
A software engineering research project by a consortium of US universities.

Archie
A program that helps Internet users find files. Participating Internet host computers download a listing of their files to Archive servers, which index these files. Users can then search this index and transfer these files using FTP. Archie functions as an archive utility, hence its name.

Archie
An archive server database and query system operated by the McGill University School of Computer Science. Services remote requests for information on software kept on archives worldwide and available via ftp.

ARCHIVE
(1) A term used to describe a server containing a large amount of publicily accessible software.
(2) A term used to describe a file which contains one or more files that have been compressed and stored.

ARCS see ARC.

ARE
All Routes Explorer: A specific frame initiated by a source which is sent on all possible routes in Source Route Bridging.

Argument
something that appears on the command line after the command.Suppose that you type this line. cp old.file new.file In this command, cp is the name of the command or program, old.file is the first argument, and new.file is the second argument.
Arguments A parameter that is passed to a function when it is called.
Arguments are specified within parentheses in the function call.

Arjuna
A system for reliable distributed computing from the Computing Laboratory, University of Newcastle upon Tyne. It supports atomic transactions on persistent objects.

ARL
ASSET Reuse Library.

ARL
Association of Research Libraries (North America).

ARP
Address Resolution Protocol: The procedures and messages in a communications protocol which determines which physical network address (MAC) corresponds to the IP address in the packet.

ARP (Address Resolution Protocol)
IP address to hardware address translation protocol.

ARPANET
U.S. Department of Defense (DARPA) wide area network. It became operational in 1968 and was the forerunner of the Internet.

ARPANET
ADVANCED RESEARCH PROJECT AGENCY NETWORK

Array
A set of variables that can be referred to with the same name and a number, called an index.

Article
The base component of USENET news; a group of text written and posted to a network news group.

Artifex
A CASE environment from ARTIS of Turin for the development of large event-driven distributed systems. It has code-generation and rapid prototyping features.

Artificial Intelligence
The subfield of computer science concerned with the concepts and methods of symbolic inference by computer, and the symbolic representation of the knowledge to be used in making inferences.

ASCII
AMERICAN STANDARD CODE FOR INFORMATION INTERCHANGE

ASCII
American Standard Code For Information Interchange. ASCII defines the codes the computer uses internally to store letters, numbers punctuation, and some control codes. Almost all Unix computers use ASCII(except some mainframes).

ASDL
Abstract-Type and Scheme-Definition Language: developed as part of Esprit project GRASPIN, as a basis for generating language-based editors and environments. It combines an object-oriented type system, syntax-directed translation schemes and a target-language interface.

ASE
Advanced Software Environment: an object-oriented application support system from Nixdorf.

ASIC
Application-Specific Integrated Circuit: an integrated circuit designed to perform a particular function by defining the interconnection of a set of basic circuit building blocks drawn from a library provided by the circuit manufacturer.

ASIS
Ada Semantic Interface Specification. An interface between an Ada library and any tool requiring information in it.

ASIS
Application Software Installation Server at CERN.

ASME
American Society of Mechanical Engineers: involved in CAD standardisation.

ASN.1
Abstract Syntax Notation 1: an ISO/CCITT standard for the description of data. It is intended to facilitate the exchange of data between application programs.

ASP
ASP stands for Active Server Pages. This is another form of programming that is only available on servers that run NT for their Operating System.

ASP
Abstract Service Primitive: An implementation-independent description of an interaction between a service-user and a service-provider at a particular service boundary, as defined by Open Systems Interconnection (OSI).

ASPECT
An IPSE developed by an Alvey project, using Z to specify the object-management system and tool interface.

Aspect Ratio
The ratio of height to width. Typical aspect ratio for a monitor is 4:3 or 1.33. Ex.: 640 / 480 = 1.33.

ASQ
Automated Software Quality. The use of software tools, such as automated testing tools, to improve software quality.

ASQC
American Society for Quality Control.

ASSET
Asset Source for Software Engineering Technology. A programme to promote software reuse by the DoD.

Assigned Cell
Cell that provides a service to an upper layer entity or ATM Layer Management entity (ATMM-entity).

Asynchronous Digital Subscriber Line (ADSL)
An asymmetric high-speed digital network connection, usually between a home or small business and a telecommunications vendor, providing an always-up direct connection to an Internet Service Provider (ISP). The upstream (from the user to the ISP) and downstream (from the ISP to the user) speeds are dissimilar, and usually the latter is faster than the former. See also Digital Subscriber Line (DSL), Symmetric Digital Subscriber Line (SDSL).

Asynchronous Data Transmission
A type of communication that sends data using flow control rather than a clock to Synchronize data between the source and destination.

Asynchronous Time Division Multiplexing
A multiplexing technique in which a transmission capability is organized in a priori unassigned time slots. The time slots are assigned to cells upon request of each application's instantaneous real need.

Asynchronous Transfer Mode (ATM)
A standardized format for cell relay, with 53-byte cells including a five byte header and 48 bytes of data. Also, the layer in the protocol stack that translates the cells to the physical media.

AT-commands
Set of protocols that allow mobile phones and modems to be controlled.

AtFS
Attributed File System: the basis of the Shape_VC toolkit. A status model controlling visibility of version objects, locking, and “long transactions” for synchronizing concurrent updates supports cooperative work within projects. The concept of object attributes provides a basis for storing management information with versions and passing this information between individual tools. This mechanism is useful for building integrated environments from a set of unrelated tools.

Athena
Project Athena: a distributed system project for support of educational and research computing at MIT. Much of the software developed is now in wider use, especially the X Window System.

Atherton
Atherton Technology developed the Software BackPlane CASE framework. Their Atherton Tool Integration Services were the basis for the ATIS standard.

ATIS
A Tools Integration Standard: an object-oriented interface to a set of services that allows the saving, accessing, and managing of information in a common repository. Developed by Atherton Technology and DEC, based on an extended version of the Software BackPlane, now proposed as an industry standard.

ATK
The Andrew Toolkit

ATM
Adobe Type Manager.

ATM
Asynchronous Transfer Mode: A transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic.

ATM Adaptation Layer
The layer in the ATM protocols that represents layers four through seven in the OSI seven layer protocol stack. The protocol that turns packets into cells.

ATM Address
Defined in the UNI Specification as 3 formats, each having 20 bytes in length including country, area and end-system identifiers.

ATM Forum
A group of organizations responsible for determining the ATM standards and its progress within the industry.

ATM Layer Link
A section of an ATM Layer connection between two adjacent active ATM Layer entities (ATM-entities).

ATM Link
A virtual path link (VPL) or a virtual channel link (VCL).

ATM Peer-to-Peer Connection
A virtual channel connection (VCC) or a virtual path connection (VPC).

ATM Traffic Descriptor
A generic list of traffic parameters that can be used to capture the intrinsic traffic characteristics of a requested ATM connection.

ATM User-User Connection
An association established by the ATM Layer to support communication between two or more ATM service users (i.e., between two or more next higher entities or between two or more ATM-entities). The communications over an ATM Layer connection may be either bidirectional or unidirectional. The same Virtual Channel Identifier (VCI) issued for both directions of a connection at an interface.

ATS
Abstract Test Suite: A set of abstract test cases for testing a particular protocol. An "executable" test suite may be derived from an abstract test suite.

Attachment
A file included as part of a MIME-compliant or NeXTMail message. An attachment can be sound, graphics, a document file (with text, formatting, and/or graphics), motion pictures, and so on.

ATTACHMENT
An attachment is a file that accompanies an e-mail message. While a message is always comprised of text characters, an attachment can be any type of file.

Attenuation
The process of the reduction of the power of a signal as it passes through most media. Usually proportional to distance, attenuation is sometimes the factor that limits the distance a signal may be transmitted through a media before it can no longer be received.

Audit trail
A file or database that contains a list of changes made to a specific file. The information includes the name of the file, the date and time of the change, the person making the change, and the text of the change itself.

AUIS
Andrew user Interface System.

Authentication
Verification of the identity of a principal.

Authoritative
A DNS server with all the records for a given domain. (Note that the authorization may not have been granted or delegated to the DNS server.)

Authority
The group responsible for administering a DNS domain.

Authorization
Verification that a principal has sufficient privilege to perform some specific operation.

AutoCAD
A CAD software package for mechanical engineering marketed by AutoDesk Inc.

Automatic Ring Down (ARD)
A dedicated point-to-point voice facility between two offices of a trading facility. When the sender picks up the telephone handset, automatically ring the receiver's end for direct connections, without the need to dial.

Autonomous System
Internet TCP/IP terminology for a collection of gateway (routers) that fall under one administrative entity and cooperate using common Interior Gateway Protocol (IGP).

AUTORESPONDER
Not surprisingly, an Autoresponder automatically responds to anyone that sends mail to it. These are used for a few things, including vacation notices and easy dissemination of information. If you had a vacation autoresponder for instance, you could turn it on when you leave, and anyone that sends mail to your address while you're gone will get an immediate response stating that you are out of town. Businesses use Autoresponders for getting sale information, new product announcements, e-mail brochures and more out to interested customers.

AVL
Abstract Visualization Language in the Tecate project.

AVS
Application Visualisation System: a portable modular UNIX-based graphics package supported by a consortium of vendors including Convex, DEC, IBM, HP, SET Technologies, Stardent and WaveTracer - .

AWK
A pattern scanning and processing language named after its authors: Aho, Weinberger and Kernighan.

aXe
A text editor for the X-Window-System.