UniForum's Open Systems Glossary

All technical languages breed their share of acronyms and our industry is no exception. UniForum's Open Systems Glossary contains Acronyms which we believe will be of use to all members. We don't expect we've captured them all, and new ones pop up all the time. We welcome new submissions (together with short to-the-point definitions) via e-mail to pubs@uniforum.org.

4GL (Fourth-Generation Language)
High-level programming languages generally associated with database applications. The name is derived from a comparison with languages such as C, which are labeled 3GLs. 4GLs are increasingly associated with graphical development tools which automatically generate the text of the programming language.

8-Bit Character Set
Character set than can be defined within the ANSI Latin-1 definition: usually around 200 characters total. See Bit.

IEEE 802.3 LAN specification using unshielded twisted-pair wiring and running at 10 Mbps. 10BaseT and Ethernet are very similar.

16-Bit Character Set
Character sets that require more than 200 characters, often considerably more: 16-bit character sets of 1,000 or more characters are common. See Bit.

100Base TX
See Fast Ethernet

100VG AnyLAN
An alternative 100 Mbps specification to Fast Ethernet. 100VG AnyLAN was sent to the 802.12 Token-Ring working group. 100VG is an attempt to make a faster Ethernet better suited to multimedia LAN communication. See also Fast Ethernet.

ABI (Application Binary Interface)
Application interfaces that enable binary applications to function compatibly on operating system environments with minor differences, such as varying implentations of UNIX System V for Intel-based computers.

AFS (Andrew File System)
An alternative networked file system developed at Carnegie Mellon University as part of Mach and later incorporated into the OSF/1 operating system. See NFS.

A simple name substituted for a complicated name, e-mail address, or company. Used frequently as an easily remembered name for an e-mail address or a list of e-mail addresses.

Anonymous FTP
A process for document retrieval using the FTP. The user logs on (as "anonymous") but does not need a password to access documents on the server. See FTP.

Second-generation specification of the C programming language accepted by ANSI in the late 1980s. Many of the changes between K&R C and ANSI-C simply formalized popular extensions that had been created within the programming community, and specified a standard library.

ANSI (American National Standards Institute)
The coordinating body for voluntary standards groups within the United States. ANSI is a member of the International Organization for Standardization (ISO).

API (Application Programming Interface)
A specification of function-call conventions that define an interface to a service. If two incompatible computers both support the same API, then a single version of source code should compile on each.

A series of related communication protocols introduced and maintained by Apple Computer. Two phases currently exist: Phase I and Phase II. Phase II, the more recent version, includes support for internetworks.

A search device for documents using anonymous FTP server machines, it is a system for locating information in files and directories that are publicly available.

ARP (Address Resolution Protocol)
A method of finding a host's Ethernet address via the broadcast mechanism; a sender using ARP broadcasts a packet containing the Internet address of another host and waits for it (or some other host) to send back its Ethernet address. Each host maintains a cache of address translations to reduce delay and loading. ARP allows the Internet address to be independent of the Ethernet address but it only works if all hosts on the net support it.

ASCII (American Standard Code for Information Interchange)
An eight-bit code for character representation; includes seven bits plus parity. See EBCDIC, UniCode.

ASIC (Application-Specific Integrated Circuit)
A custom computer chip designed to perform a specialized function, hence application-specific.

AT/IDE (Integrated Drive Electronics)
The IBM AT hard disk controller interface that was moved off dedicated controller cards and onto the actual drive electronics (hence the name). The IDE interface is inexpensive and widely used but limits the system to two devices, a master and a slave. An updated specification, called ATA, is being discussed.

ATM (Asynchronous Transfer Mode)
A CCITT standard for cell relay. Multiple types of information, such as voice, video and data, are conveyed in small, fixed-size cells. Also, a BISDN transfer mode wherein an accelerated version of asynchronous time division multiplexing (ATDM) is used to move multiple streams of information across a communication channel. ATM is both a LAN and WAN technology.

Backbone in a Box
Using a router with a high-speed backbone to function as a network backbone. All primary LAN segments are run to the router, and communication between those segments flows at high speed. It is easy to integrate several protocols, and the router centralizes backbone management.

Backbone Network
The central data highway that connects other networks. A backbone can be the network infrastructure that connects several LAN segments within a building or campus, or a national or international infrastructure connecting network operations in various cities.

The capacity of a network, usually measured in bits per second. Network systems need higher bandwidth for audio or video than for e-mail or other services.

Literally, the number of times per second the signal can change on a transmission line. Usually, the buad rate equals the number of bits per second that can be transferred.

BBS (Bulletin Board Service)
A service that permits one person to post a message for others to read. Each bulletin board contains the discussion of a single topic. A bulletin board is sometimes called a computer conference.

Binary File
A file with nontext characters. Often, a directly executable file that can be run as a program. Binary characters use all the bits in a (8-bit) byte. See also ASCII.

BISDN (Broadband ISDN)
Communication standards being developed by the CCITT to handle high-bandwidth applications such as video. BISDN can use ATM technology over SONET-based transmission circuits to provide data rates of 155 Mbps to 622 Mbps and beyond. Other physical layers can be used (T1, T3). See BRI, ISDN and PRI.

Bit (Binary Digit)
A unit of information; the amount of information obtained by asking a yes-or-no question. A computational quantity that can take on one or two values, such as true or false or 0 or 1. The smallest unit of storage - sufficient to hold one bit.

A commercial PC file transfer and terminal emulation package marketed by a division of U.S. Robotics.

Bps (Bits per Second)
Literally, a measure of the rate of data transmission. Usually, the measure refers to the capacity of a network. See Bandwidth.

BRI (Basic Rate Interface)
The ISDN interface composed of two B channels and one D channel for circuit-switched communication of voice, data and video. See BISDN and ISDN.

Broadband communications can carry multiple types of information by allocating different services to different frequencies. This characteristic enables it to more easily accommodate voice, video, and data.

Another term for "viewer"; that is, a software package that permits you to look around the World Wide Web. Examples of a browser are Netscape or Mosaic.

BSD (Berkeley Software Distribution)
A UNIX version released by the University of Calif. at Berkeley's Computer Systems Research Group, sold only to AT&T UNIX licensees because it contains some AT&T source code. Earlier versions of SunOS were derived from BSD roots. A commercial implementation of BSD, cleansed of AT&T source code, is available from BSDI.

An amount of memory or data, usually eight-bits; the smallest unit of memory referenced by an addressable unit of storage.

A programming language, originally developed by Ken Thompson and Dennis Ritchie. C has since been extended and standardized and is used throughout the world.

An object-oriented programming (OOP) extension of the C programming language. OOP languages offer improved ability for developers to reuse software modules but require a fundamentally different mindset in development projects.

A small, fast memory holding recently accessed data, designed to speed up subsequent access to the same data. Most often applied to processor-memory access but also used for a local copy of data accessible over a network, etc.

CAD (Computer-Aided Design or Drafting)
CAD and related terms are often used with varying meanings. Generally CAD refers to the computer-based design work or architects, civil and mechanical engineers, etc. Some call this MCAD (Mechanical CAD).

CAE (Computer-Aided Engineering
Generally refers to the computer-based design, simulation and testing work of electrical engineers. Some refer to this market as ECAD (Electrical CAD).

CAM (Computer-Aided Manufacturing)
Generally refers to the use of computers in the manufacturing process. Manufacturing equipment is increasingly fitted with computer-based monitoring components, and some are computer-controlled. Centralized, real-time computer monitoring of manufacturing processes is now common.

CASE (Computer-Aided Software Engineering)
Computer-based software design tools (Upper CASE) and code-generation tools (Lower CASE). CASE generally refers to software development tools intended for the development of large, complex projects, often by large development staffs.

CAT (Common Abstract Tree Language)
A universal intermediate language, used by Norsk Data in their family of compilers. It is a multi-language compiler system with automatically generated code generators.

CBT (Computer-Based Training)
Software applications generally designed for self-paced, independent learning. CBT often enables trainees to work through what-if scenarios.

CCD (Computer-Created Design)
A design created by computer.

See ITU.

CDDI (Copper Distributed Data Interface)
Standard for FDDI implementation on top of existing twisted-pair copper cable.

CD-ROM (Compact Disk Read- Only Memory)
Generally mass produced compact disks with computer applications and data. Data can only be read from, not written to, these optical disks. See WORM.

CDE (Common Desktop Environment)
A specification under review by X/Open to establish a common graphical user interface. Part of COSE.

Cell Relay
The basis of several high-speed network protocols, including the SMDS Interface Protocol and ATM. Small, fixed-size packets, or cells, contain identifiers specifying the data stream to which they belong. Fixed-length cells can be processed and switched in hardware at very high speeds.

Particle physics institute located in Geneva, Switzerland. It is the home of the World-Wide Web.

CGM (Computer Graphic Metafile)
A type of file used for graphics.

Character Set
Mapping of numeric values to specific characters, as with ASCII, ISO 8859 (Latin-1), and so on.

CIM (Computer Integrated Manufacturing)
An alternative term for CAM. Manufactuing equipment is fitted with computer-based monitoring or control components and networked so that manufacturing processes can be monitored in real-time.

CISC (Complex Instruction Set Computing)
A type of CPU. CISC processors use a more complex instruction set with multiple operand addresses, which may be out of memory. Intel 80386 and 80486 processors are CISC CPUs. RISC processors, in contrast, are more efficient and faster.

The computer running client software that connects to server machines holding information; the client makes requests to a server for documents and is responsible for displaying the information.

Client/Server Computing
The interaction between two programs when they communicate across a network. A program at one site sends a request to a program at another site and awaits a response. The requesting program is called a client; the program satisfying the request is called the server.

A particular set of characters. See Character Set.

A translator that produces an executable file from a collection program source code.

CORBA (Common Object Request Broker Architecture)
A specification jointly published by OMG and X/Open, to define a software layer responsible for accepting and fulfilling requests for objects. Version 1.1 was completed in 1991. Version 2.0 is, among other things, tackling interoperability issues.

COSE (Common Open Software Environment)
A process undertaken initially by Sun Microsystems, IBM, Hewlett-Packard, USL (Novell) and SCO to develop com- mon sets of specifications and interfaces to promote greater interoperability. COSE has generally deferred to X/Open's formal standardization process where X/Open is actively addressing issues.

CPU (Central Processing Unit)
The microprocessor responsible for the core processing of computers - the brain that coordinates all the computer's functions.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
The channel access method used in Ethernet and IEEE 802.3. If two devices transmit simultaneously, a collision occurs, and both devices wait a random period of time before retransmission.

CSO (Central Services Organization)
A service which facilitates user and address lookup in databases.

A library designed at U.C. Berkeley to draw on a character-mode CRT screen in a terminal-independent fashion. Curses is included with every UNIX release and is now available for many non-UNIX environments, such as DOS.

DAT (Digital Audio Tape)
Refers to a specification that enables digital data to be written to tape in an form factor similar to audio tape. Because DAT devices are generally less expensive and smaller, they have become popular backup devices for stand-alone personal computers.

DBMS (Database Management System)
A generic term referring to a variety of software applications designed to enable users to enter, store, manipulate and retrieve data. Relational DBMS are most common. Some low-end DBMSs, as well as large-scale mainframe DBMSs are flat-file databases. Object DBMS are a relative newcomer that is popular for some applications.

DCE (Distributed Computing Environment)
DCE is an application suite developed by OSF and focused upon communications, distributed file services, naming services and security. Both DCE and ONC, an alternative, are supported by COSE member companies.

DDE (Dynamic Data Exchange)
An MS Windows service enabling applications to share data. For example, DDE could enable a spreadsheet to be shared with a word processing application.

A group of communications products (including a protocol suite) developed by Digital Equipment Corp. The most recent iteration is DECnet Phase V, which is largely based on the OSI protocols.

DES (Data Encryption Standard)
Standard cryptographic algorithm developed by the U.S. National Bureau of Standards.

Digital-to-Analog Converter
An electronic device that converts a sequence of numbers into an analog electrical signal. As one example, a D-to-A converter is needed to change the numbers on a compact disc into sounds.

DMA (Direct Memory Access)
A scheme where controllers access memory on a system without CPU intervention. For example, many PC SCSI controllers perform their own DMA to/ from memory, thus eliminating the CPU overhead found in "programmed I/O" environments like the PC AT/IDE interface, which requires that the CPU read or write all data from or to the IDE device.

DME (Distributed Management Environment)
An OSF suite of services and applications for distributed system and network management.

DNS (Domain Name System)
Distributed name system used primarily to locate host IP addresses based upon host names. It consists of a hierarchical sequence of names, from specific to general.

DPI (Dots Per Inch)
Literally, the number of dots printed or displayed in one inch. Usually used to describe printer and scanner resolutions, but sometimes to describe computer graphics monitors.

DQDB (Distributed Queue Dual Bus)
Communication protocol proposed by IEEE 802.6 committee for use in MANs.

Dedicated 56 Kbps digital lines. DS0 lines are the most common private lines in use. See T1, T3.

DSP (Digital Signal Processing)
A chip dedicated to processing data such as voice and music. In much the same way as a floating-point processor off-loads math functions from the CPU, the DSP off-loads a lot of the load in multimedia applications.

DTMF (Dual Tone Multifrequency)
Use of two simultaneous voice-band tones for dialing (such as touch tone).

DTP (Desktop Publishing)
A computing market generally referring to graphical page design and layout software, and related peripherals. In some quarters "DTP" is developing a low-end, amateurish, connotation, while "electronic publishing" is used for commercial computer-based publishing work.

EBCDIC (Extended Binary Coded Decimal Interchange Code)
An eight-bit character code developed by IBM for data representation in their large mainframe computer systems.

EDI (Electronic Data Interchange)
The electronic communication of operation data such as order and invoices between organizations.

EISA (Extended Industry Standard Architecture)
An alternative to the IBM PC/XT/AT ISA architecture. EISA cards are software configured, so jumpers are eliminated, and can access system resources via a 32-bit bus. It also is backward-compatible to eight- and 16-bit ISA cards.

Electronic Mail
A service that permits one to send text to another person, a group, or a computer program. Messages automatically pass from one computer to another through computer networks and/or via modems over telephone lines. Electronic mail software permits, for example, one to reply to a memo, save it, and many other features. Usually stored as text files.

An abbreviation for electronic mail.

ESDI (Enhanced Small Device Interface)
ESDI is an aging hard disk controller specification, which provided substantially better performance than the ST-506 interface. See SCSI.

ESQL (Embedded SQL)
The inclusion of SQL statements within another programming language (such as C), making it easier to integrate external application modules or procedures with a database.

A baseband LAN specification invented by Xerox Corp. and developed jointly by Xerox, Intel, and Digital Equipment Corp. Ethernet networks operate at 10 Mbps using CSMA/CD to run over coaxial cable. Ethernet is similar to a series of standards produced by IEEE and referred to as IEEE 802.3.

Ethernet Address
The physical address identifying a controller board. The Ethernet address is hard-wired on some controllers or stored in a ROM, and others allow it to be charged from software.

Ethernet Switching
A strategy to dedicate the full bandwidth of an Ethernet connection between two network devices, such as a workstation and a switching hub. Full duplex switched Ethernet offers a theoretical bandwidth of 20 Mpbs (10 in each direction), while standard switched Ethernet provides 10 Mbps.

FAQ (Frequently Asked Questions)
FAQ is seen quite often on World-Wide Web pages. It is a place where people can get most of their questions answered without having to contact the Webmaster.

Fast Ethernet
A proposed specification in the 802.3 Ethernet working group to boost Ethernet speeds to 100 Mbps, and referred to as 100BaseTX. Early implementations promise to offer automatic sensing of LAN speeds between 10 Mbps and 100 Mbps. See also 100VG AnyLAN.

FDDI (Fiber Distributed Data Interface)
An ANSI-defined standard specifying a 100 Mbps token-passing network using fiber-optic cable. Uses a dual-ring architecture to provide redundancy.

FIFO (first in, first out)
A form of queuing where the order of removal from the queue is the same as the order of insertion into the queue. Hardware FIFOs are often used to buffer data streams between devices that may transfer data at different rates.

FIPS (Federal Information Processing Standard)
A collection of standards and specifications endorsed by the U.S. government, in its attempt to achieve greater interoperability between its hardware and software systems.

FOIRL (Fiber-Optic Inter-Repeater Link)
Fiber-optic signaling methodology based on the IEEE 802.3 fiber-optic specification, which allows Ethernet and IEEE 802.3 traffic to pass over fiber-optic cabling.

Frame Relay
A WAN protocol generally considered a replacement for X.25, providing more efficient transmission. Frame Relay is offered at speeds from 56 Kbps up to T1 speeds.

FTP (File Transfer Protocol)
A high-level Internet file transfer protocol, usually implemented at the application layer.

A graphic image format in common use.

GIS (Geographic Information System)
A category of highly visual and graphical applications designed to present information within its geographic context, usually as an overlay to a map or satellite image. Often used for urban growth management, natural resource planning, or to determine the best location for a retail outlet.

GNU (Gnu's Not UNIX)
Developed by Richard Stallman, then of MIT, now with the Free Software Foundation, a UNIX-look-alike operating system more similar to BSD than System V.

A distributed document retrieval system developed by the University of Minnesota. Gopher servers organize information in a menu hierarchy, and menu selections may reference files on other Internet hosts.

GOSIP (Government OSI Profile)
A government procurement specification for OSI protocols. Through GOSIP, the government has mandated that all federal agencies standardize on OSI and implement OSI-based systems as they become commercially available.

GUI (Graphical User Interface)
A general term used to distinguish newer application presentation methods, such as Motif, OpenLook, MS Windows and Macintosh OS, from applications displayed on character-based terminals. GUIs are characterized by multiple overlapping, resizable windows, buttons, and the ability to use pointing devices, such as a mouse.

HIPPI (High-Performance Parallel Interface)
High-performance network interface standard defined by ANSI.

Home Page
Start-up document that serves as home base for Internet explorations.

A computer connected to a network,. Also called a "node."

HTML (Hypertext Markup Language)
HTML is the page description language used to format pages for viewing in the World-Wide Web. Formatting tags are embedded in a text file. These formatting commands are interpreted when the document is viewed with a Web browser, such as Netscape. A superset of HTML, called HTML+, is being proposed to extend the language. HTML is derived from SGML and uses hypertext.

HTTP (Hypertext Transfer Protocol)
HTTP is the client-server TCP/IP protocol used on the World-Wide Web for the exchange of documents.

Word or graphic in a file displayed on screen with some form of highlighting (color or underlining or both). The word or graphic represents hidded text containing the URL information of another document, which is displayed when you click on the highlighted word or graphic.

A system for storing pages of textual information that each contain embedded references to other pages of information.

I/O (Input/Output)
Input and output of text from software or hardware.

IAB (Internet Architecture Board)
The group responsible for guiding the research and development of the Internet. They are all volunteers who attend to hear about the latest developments and participate in efforts to refine and improve the software. It has two task forces: the IETF and the IRTF.

IEEE (Institute of Electrical and Electronics Engineers)
A professional and trade association that also promulgates information industry standards. IEEE LAN standards are the predominant LAN standards today, including protocols similar or virtually equivalent to Ethernet and Token Ring. See POSIX.

IEEE 802.3
LAN protocol that specifies an implementation of the physical layer and MAC sub-layer of the link layer. IEEE 802.3 uses CSMA/CD access at a variety of speeds over a variety of physical media. One physical variation of IEEE 802.3 (10Base5) is very similar to Ethernet.

IEEE 802.6
IEEE MAN specification based on DQDB technology. It supports data rates of 1.5 Mbps to 155 Mbps, and also supports data packets and circuits.

IETF (Internet Engineering Task Force)
The primary subgroup responsible for technical matters within the IAB.

A working version of a specification, such as a programming language or an application.

Information Superhighway
A term used by the popular press to refer to the emerging national information infrastructure in the United States. The Internet is the best example of the first part of the information infrastructure.

The Internet consists of thousands of computer networks interconnected by routers. It is an extensive computer network that is accessed through the telephone system making it possible to reach millions of people all over the world. The IP transforms a collection of networks and routers into a seamless communication system by making the Internet function like a single, large network.

IP (Internet Protocol)
A Layer 3 (network layer) protocol that contains addressing information and some control information that allows packets to be routed. See TCP/IP.

IPX (Internetwork Package Exchange)
Novell Layer 3 protocol similar to XNS and IP that is used in NetWare networks.

IRQ (Interrupt Request Line)
A hardware signal (bus line) that allows a peripheral device to request processing by the CPU.

IS (Information Systems)
Information pertaining usually to computer systems.

ISA (Industry Standard Architecture)
The name given to the original PC/XT/ AT bus designed by IBM in the early 1980s. The bus supports both eight- and 16-bit-wide devices as well as a degree of board vendor independence. See EISA, MCA.

ISAM (Indexed Sequential Access Method)
A somewhat crude but effective database format that originated in the mainframe world. Records in the database are logically accessed sequentially, by walking through the database index in the desired order.

ISDN (Integrated Services Digital Network)
Communication protocols used by telephone companies to permit telephone networks to carry text, voice and other types of data. ISDN typically operates at 56/64 Kbps. See BRI, BISDN, and PRI.

ISO (International Organization for Standardization)
An international organization that is responsible for a wide range of standards, including those relevant to networking. ISO is responsible for the well-known OSI networking reference model. Often incorrectly referred to as the International Standards Organization.

IT (Information Technology)
Information pertaining to Technology.

ITU (International Telecommunications Union)
The renamed CCITT. The standards setting functions are handled by the ITU-T, the Telecommunications Standardization Sector.

JPEG (Joint Photographic Experts Group)
The original name of the committee that designed the standard image compression algorithm. The algorithm, JPEG, is designed for compressing either full color or grey-scale digital images of "natural," real-world scenes.

Jughead (Jonzy's Universal Gopher Hierarchy Excavation And Display)
A tool for gopher administrators to get menu information from various gopher servers across the Internet.

Kbps (Kilobits per second)

K&R C (Kernigan & Ritchie C)
The original C programming language as specified by Brian W. Kernighan and Dennis M. Ritchie. C is a relatively low-level, highly portable, general-purpose programming language created by Ritchie on the UNIX operating system. See ANSI-C.

A popular, public-domain file-transfer program.

The part of the operating system that provides memory management, I/O services, and all other low-level services. The kernel is the "core" or "heart" of the operating system.

LAN (Local-Area Network)
A network covering a relatively small geographic area (usually not larger than a building or campus). Compared to WANs, LANs are usually characterized by relatively high data rates and relatively low error rates. See WAN, MAN.

LEC (Local Exchange Carrier)
Local telephone companies, including the RBOCs and other specialty and private companies.

LIFO (Last In, First Out)
Better known as a "stack," a LIFO queue behaves opposite of a FIFO queue. A LIFO queue only allows access to the most recently queued item, then the next most recently, etc. This form of queuing is most often used to "stack" the return addresses when performing subroutine calls.

Software that distributes e-mail messages to registered subscribers such as major-domo, listserv, etc. Automates most all the processes necessary to enable distributed discussion groups via e-mail.

MAN (Metropolitan-Area Network)
Generally, a network that spans a larger geographic area than a LAN but a smaller geographic area than a WAN. See DQDB.

Mbps (Megabits Per Second)

MCA (Micro Channel Architecture)
An IBM proprietary bus architecture used in most of the PS/2 series of machines and the RS/6000 line of workstations and servers. The architecture supports multiple CPUs on the bus, like EISA and unlike ISA.

MFLOPS (Million Floating-Point Operations Per Second)
A measurement of speed in handling complex calculations, based upon floating-point arithmetic. See MIPS.

MHS (Message-Handling System)
A CCITT X.400 recommendation that provides message handling services for communications between distributed applications. NetWare MHS is a different, although similar, entity that also provides message-handling services and is marketed by Novell.

MHz (Megahertz)
Literally, millions of Hertz (cycles per second). MHz is an indication of frequency, often used to refer to the clock speed at which a given processor or bus runs, and named to honor Heinrich Hertz.

MIF (Maker Interchange Format)
A text format used by FrameMaker to exchange files across platforms.

MIME (Multimedia Internet Mail Extensions)
A method of processing multipart, multimedia messages on the Internet.

MIPS (Million Instructions Per Second)
The performance measure for modern CPUs. See MFLOPS.

MIS (Management Information Systems)
Generally refers to corporate business computing services and the department responsible for them.

NCSA's browser (client) for the World-Wide Web. Mosaic is a true second generation Internet client application for browsing HTML documents on the World-Wide Web. It supports full multimedia capabilities, and has been 0extended to access gopher servers, as well as handle news and e-mail. It is now being licensed and bundled with some operating systems.

A graphical user interface developed by OSF and now endorsed as part of COSE.

MPEG (Moving Pictures Experts Group)
An ISO committee that generates standards for digital video compression and audio. Also the name of their algorithm.

MRP (Manufacturing Resource Planning)
Computer systems and software used in planning an procurement of materials.

MSC (CCITT Message Sequence Charts)

MTA (Message Transfer Agent)

MTBF (Mean Time Between Failure)
An indication of expected duration between successive failures of a given device. MTBF ratings are usually specified to give an indication of the expected or predicted reliability under specific operating conditions. For example, most disk drives today have predicted MTBF values between 100,000 and 800,000 hours.

NAS (Network Applications Support)
A broad middleware architecture designed by Digital Equipment Corporation to enable application interoperability over a network of heterogeneous computer systems.

NCSA (National Center for Supercomputing Applications)
The birthplace of the first version of the Mosaic World-Wide Web browser, at the University of Illinois at Urbana-Campaign, IL, USA.

Net, The
A term for two particular networks: Usenet and Internet. For instance, "I read it on The Net" or "You can get that file on The Net."

A network management architecture, operating system and related applications, commercially developed and sold by Novell.

Hardware and software data communications systems. Networks are often also classified according to their geographical extent: LAN, MAN, WAN, and also according to the protocols used.

NFS (Network File System)
As commonly used, a distributed file system protocol suite developed by Sun Microsystems that allows remote file access across a network. In actuality, NFS is simply one protocol in the suite. RNFSS protocols include NFS, XDR (External Data Representation), RPC (Remote Procedure Call) and others. These protocols are part of a larger architecture that Sun refers to as ONC (Open Networked Computing).

NIST (National Institute of Standards and Technology)
Formerly the National Bureau of Standards (NBS), this U.S. government organization supports and catalogs a variety of standards.

NMS (Network Management System)
A system responsible for managing part of a network. An NMS is generally a reasonably powerful and well-equipped computer such as an engineering workstation, with a megapixel color display, large memory and disk space, and a fast processor. NMSs communicate with agents to help keep track of network statistics and resources. See SNMP.

NNTP (Network News Transfer Protocol)
A common method by which articles are transferred over Usenet.

NSF (National Science Foundation)
A federally funded organization that manages the NSFnet, which connects every major research institution and campus in the United States.

Apple Computer's bus architecture used in its Macintosh systems.

OCR (Optical Character Recognition)
The ability to scan text and have the computer recognize letters, words and text formats on a page. OCR enables computers to turn images of documents into text files that can be edited in word processing applications.

ODBMS (Object Database Management System)
Sometimes referred to as Object-Oriented DBMS. ODBMSs emphasize data classes and methods. Proponents claim object databases excel at storing complex groups of data as single objects. Examples might include a parts schematic or CAD diagram.

OEM (Original Equipment Manufacturer)
Use varies, but literally refers to the manufacturer or designer of a technology, which then licenses the technology to another company.

OLAP (On-Line Analytical Processing)
Database processing that supports advanced decision support, often using a multidimensional database.

OLTP (On-Line Transaction Processing)
Database processing that supports data entry at high speeds, such as traditional high-volume order-entry applications.

OMG (Object Management Group)
An industry group promoting standards for exchanging objects in an interoperable manner, perhaps best known for its work on CORBA.

OMT (Object Modeling Technique)
An object-oriented programming strategy.

ONC (Open Network Computing)
Sun Microsystems network protocols.

The graphical user interface developed by AT&T and Sun Microsystems. Until recently, a competitive peer to Motif. With COSE, Sun has acquiesced to Motif as the standard UNIX windowing environment.

OS (Operating System)
The software on a computer that manages all the resources of the system, including file system management, memory, reading and writing files, scheduling processes, printing and communication

OSF (Open Software Foundation)
An industry consortium responsible for the development of Motif, OSF/1, DCE and DME.

OSI (Open System Interconnection)
An international standardization program created by ISO and CCITT to develop standards for data networking that facilitates multivendor equipment interoperability. The OSI seven-layer model is frequently used to describe the various levels of network technology.

PA-RISC (Precision Architecture- RISC)
Hewlett-Packard's microprocessor architecture.

A unit of data sent across a network.

PBX (Private Branch Exchange)
A telephone switch on the user's premises.

PC (Personal Computer)
A general-purpose single-user microcomputer designed to be operated by one person at a time.

PCI (Peripheral Component Interconnect)
A self-configuring personal computer local bus designed by Intel. It runs at 33 MHz. It is currently used mostly on Pentium-based computers, but is processor independent and so can work with other processor architectures such as PowerPC and Motorola 680X0 series.

PCL (Printer Control Language)
A proprietary vendor- and device-specific control language used for laser printer control defined by Hewlett-Packard in the 1980s.

PCMCIA (PC Memory Card International Association)
An industry standard covering the mechanical and electrical specifications needed to interface to these credit card-size hard disks, modems, network adapters and memory cards with computer systems.

PEX (PHIGS Extensions to X)
A combination of X Windows and PHIGS designed to create a networked, interoperable 3-D graphics environment.

PHIGS (Programmer Hierarchical Interactive Graphics System)
An ANSI/ISO standard 3-D graphics programming library that runs on almost all graphics computers, from laptops to supercomputers.

POS (Point of Sale)
Essentially a computer-based cash register. As the retail industry is increasingly computerized, most POS systems are computers with specialized peripherals, that are networked to an in-store server.

POSIX (Portable Operating System Interface)
IEEE's standardization effort to promote interoperable computing interfaces and specifications.

A device- and resolution-independent page definition language developed by Adobe Systems, popularized with laser printers, and used to compose documents one page at a time before printing.

PPP (Point-to-Point Protocol)
A successor to SLIP, this protocol provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. See SLIP.

PRI (Primary Rate Interface)
ISDN interface to primary rate access. Primary rate access consists of a single 64 Kbps D channel plus 23 (in the case of the 1.544 Mbps) or 30 (in the case of 2.048 Mbps) B channels for voice and/or data. See BISDN, ISDN.

The rules two or more computers must follow to exchange messages. A protocol describes both the format of data that can be sent, as well as the way a computer should respond.

Proxy ARP (Address Resolution Protocol)
The technique in which one host, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination. Proxy ARP allows a site to use a single IP address with two physical networks.

Public Key Encryption
An encryption scheme using two keys. One key is public and the other private. The message is encrypted using the intended recipient's public key. The message can only be decrypted by the recipient using the recipient's private key. See also RSA.

QBE (Query By Example)
A form of database query where the user enters a form of the database query rather than having to enter actual SQL commands.

QIC (Quarter-Inch Cartridge)
An industry standard form factor that covers tape capacities from 20 MB to several gigabytes. The QIC committee provides media specifications, the actual format of the data tracks on the tape and interoperability specifications.

A digital video format developed by Apple Computer that integrates synchronized video and audio with compression techniques.

RAID (Redundant Array of Independent Disks)
A product niche where multiple hard disk drives in a single enclosure operate in unison to increase read/write throughput, and/or increase data integrity and high availability, by continuing to function even if a single drive fails. The RAID Advisory Board has designated RAID levels 0-5 as a standard way for vendors to specify how their products read and write data.

RBOC (Regional Bell Operating Company)
The "Baby Bell" phone companies created in the divestiture of AT&T, such as NYNEX, Pacific Bell, Bell South and Ameritech.

RCS (Revision Control System)
A publicly available source code control system developed at Purdue University. Most Berkeley-style UNIX vendors ship RCS but not as part of their official OS distribution. The System V counterpart to RCS is SCCS.

RDBMS (Relational Database Management System)
The de facto database paradigm that is the core for the new generation of client/ server application infrastructures being developed. Relational database supply tables of rows and columns, making it possible to access data in a more flexible manner than in heirarchial databases.

RF (Radio Frequency)
Generic term referring to frequencies that correspond to radio transmissions. Cable TV and broadband networks use RF technology. RF is also being used to communicate between handheld client computers and database servers.

RFC (Request For Comments)
Documents used as the primary means for communicating information about the Internet. Some RFCs are designated by the IAB as Internet standards. Most RFCs document protocol specifications such as Telnet and FTP, but some are humorous and/or historical. RFCs are available from the Internet Network Information Center.

RFP (Request For Proposal)
A document generally issued by a prospective purchaser of technology systems, describing their requirements, so that prospective sellers can respond with detailed proposals.

RFS (Remote File System)
An alternative networked file system to NFS and AFS.

RISC (Reduced Instruction Set Computing)
RISC processors employ a more simple instruction set that generally executes within a single clock cycle, and makes better use of the chip's registers. This combines to provide far faster processing than chips with a CISC architecture.

RMON-MIB (Remote Monitoring - Management Information Base)
A standard developed by the Internet Engineering Task Force (IETF) recently finalized for Ethernet, but still in transition for Token Ring networks. A key benefit of the RMON-MIB is that it requires less network traffic and overhead than proxy agents.

ROM (Read-Only Memory)

A router can interconnect two networks that use different technologies. Therefore a router can connect a LAN to another LAN, to a WAN, or a WAN to another WAN.

Asynchronous, bidirectional bit-wide data standard typically used to connect peripherals (modems, printers, terminals) to computers.

The initials of the authors of a study on encryption and decryption regarding computer security. RSA Data Security markets public key or dual key encryption technology, widely used in security products.

RTF (Rich Text Format)
A file interchange format from Microsoft to facilitate document exchange.

SAA (System Application Architecture)
A broad architecture defined by IBM to integrate applications across its proprietary systems that uses SNA as its communications layer.

The bus architecture used on most SPARC workstations. SPARC multiprocessing systems generally use an additional CPU/Memory architecture (MBus).

SCCS (Source Code Control System)
A version-control utility incorporated in UNIX System V implementations. RCS is an alternative publicly available versioning system.

SCSI (Small Computer Systems Interface)
Widely used byte-wide controller interface specification standard on workstations and Macintoshes which is capable of transfering 5 MBps. Peripherals of different types (hard disks, scanners) can be combined on one SCSI bus.

Newer SCSI specification that supports a 10 MBps data transfer rate and a broader range of devices. SCSI-2 is becoming more common on high-performance systems.

SDL (CCITT Specification and Description Language)
Specification language with both graphical cna character-based syntaxes for defining interacting extended finite state machines. Used to specify discrete interactive systems such as industrial process control, traffic control, and telecommunication systems.

The computer that provides services (documents, software) to other machines that run specific software (clients) and request those services. See Client/Server Computing.

SGML (Standard Generalized Markup Language)
An ISO standard designed to ensure that electronic documentation is interoperable between dissimilar hardware and software systems. SGML is increasingly being adopted as a requirement by commercial and governmental organizations.

SIMM (Single In-line Memory Module)
A small circuit board populated with memory chips. SIMMs are considered more convenient to work with than placing or exchanging individual memory chips on a board.

SLIP (Serial Line Internet Protocol)
A protocol used to run IP over serial lines such as telephone circuits via a modem or leased lines.

SMDS (Switched Multimegabit Data Service)
A high-speed, packet-switched WAN technology offered by some RBOCs and Interexchange carriers. SMDS is generally run at speeds between DS-1 and DS-3.

SMTP (Simple Mail Transfer Protocol)
A protocol for electronic mail services popular in Internet environments.

SNA (Systems Network Architecture)
A network architecture developed by IBM in the 1970s.

SNMP (Simple Network Management Protocol)
An Internet network management protocol that provides a means to monitor and set network configuration and run-time parameters.

SNMP-2 (Simple Network Management Protocol - Version 2)
An update of the SNMP standard by the Internet Engineering Task Force (IETF). One enhancement addresses the security of network management packets.

SONET (Synchronous Optical Network)
High-speed synchronous network standard. Used by RBOCs as a transmission system for voice and data. See ATM.

Indiscriminate and unwelcome Internet advertising. Viewed as abuse of NES groups and listserver-based discussion groups.

SPARC (Scalable Processor Architecture)
The microprocessor architecture popularized by Sun Microsystems. Since it is openly licensed and supported by an independent industry consortium, SPARC is used by many other computer firms, ranging from clone and compatible vendors, specialty laptops, and even massively parallel processing supercomputers.

A floating-point performance measure developed by the Systems Performance Evaluation Cooperative, an industry consortium. SPECfp is the geometric mean of six floating-point performance benchmarks.

An integer performance measure developed by the Systems Performance Evaluation Cooperative, an industry consortium. SPECInt is the geometric mean of four integer performance benchmarks.

SQL (Structured Query Language)
A higher-level language used for database application. ANSI has certified both a 1989 and a 1992 SQL standard.

(1) An early 1980 hard disk drive interface specification named after the industry standard 5 MB (yes, five megabytes) formatted capacity. (2) A 5.25-inch disk drive using MFM encoding. See ESDI, SCSI.

SVR4 (System V Release 4)
The latest major release of the UNIX operating system from Novell's UNIX Systems Group, and the release on which most UNIX implementations are based.

System V
The current generation of the UNIX operating system produced by AT&T. The two most significant previous generations were System III and Version 7.

Digital leased-line supporting 1.54 Mbps (DS-1).

Digital leased-line supporting 44.7 Mbps (DS-3).

TCP/IP (Transmission Control Protocol/Internet Protocol)
The two best-known Internet protocols, often erroneously thought of as one protocol. TCP corresponds to Layer 4 (the transport layer) of the OSI reference model, and provides reliable data transmission. IP corresponds to Layer 3 (the network layer) of the OSI reference model and provides connectionless datagram service. TCP/IP was developed by the U.S. Department of Defense in the 1970s to support the construction of worldwide internetworks.

This utility allows the user to log into a remote computer over a network (such as the Internet) using TCP/IP. The user can work on a remote computer as if it were their local computer. The telnet program is available on many operating systems.

Terminal Emulator
A program that makes a computer display act like a terminal. For example, many terminal emulator programs emulate the Digital Equipment Corporation VT100 terminal.

Page formatting language with capabilities similar to troff, written by Donald Knuth of Stanford.

A common graphic image file format.

Token Ring
A token-passing LAN developed and supported by IBM. Network devices access the physical medium based upon possession of a small frame, called a token. Very similar to an IEEE 802.5 LAN. Operates at 4 or 16 Mbps.

TSR (Terminate and Stay Ready or Resident)
A program strategy used to work around the inherently single-user, single-tasking nature of MS DOS. Examples of common TSRs include print spoolers, keyboard enhancers and memory managers.

High-speed network developed by Ultra Network Technologies. Supports up to 125 Mbps.

64-bit Version 9 SPARC microprocessor architecture used by Sun Microsystems, HaL Computers, and licensees.

A two-byte character set developed by the UniCode Consortium, which was incorporated in 1991. UniCode integrates ASCII, Latin character sets and Far Eastern languages into a single character set.

Unshielded Twisted Pair
Standard telephone cable, rated at Category 3 or above. See 10BaseT.

UPS (Uninterruptable Power Supply)
A family of battery devices from multiple vendors that take over when normal electrical power fails. Their size, sophistication and cost vary widely.

URL (Universal Resource Locator)
An addressing syntax used on the Internet and used extensively on the World-Wide Web. URLs generally have th form service://address, such as "http://www.uniforum.org". URLs can also specify ftp, news, mail, and other internet host servers.

Usenet is a collection of thousands of computers worldwide that exchange files called news articles. This "net news" system has hundreds of discussion groups, from technical topics to art.

UUCP (UNIX-to-UNIX Copy Program)
A UNIX file transfer application that is the basis for some E-mail systems.

An international standard for 1200 bps data transmission.

v.22 bis
An international standard for 2400 bps data transmission.

An international standard for 9600 bps data transmission.

v.32 bis
An international standard for 14.4 Kbps data transmission.

A new modem serial line protocol that covers 19.2 Kbps, 24.4 Kbps, and 28.8 Kbps. With v.42 bis data compression, effective throughput can top 200 Kbps. See also v.Fast.

An international standard error-correction protocol.

v.42 bis
An international standard error-correction protocol that added data compression to the V.42 standard, allowing for speeds up to 57.6 Kbps.

The working name for the new v.34 standard that covers 19.2 Kbps, 24.4 Kbps, and 28.8 Kbps.

VAR (Value-Added Reseller)
A term whose meaning varies widely. Often a company that sells its own software together with another firm's software or hardware.

Veronica (Very Fast Rodent Oriented Net-wide Index to Computer Archives)
A service that maintains an index of titles of gopher items and provides keyword searches of those items. Veronica does for gopher servers what archie does for FTP servers.

WAIS (Wide-Area Information Servers)
WAIS is an index and retrieval system. When a keyword is entered, a search is performed on indexed documents, which then can be retrieved. It is supported by Apple Computer, Thinking Machines and Dow Jones.

WAN (Wide-Area Network)
A network spanning a large geographic area. See LAN, MAN.

The administrator responsible for the management and often is the designer of a World-Wide Web site.

A rectangular area on a screen devoted to one particular application program. Windows can overlap, and a user can move windows on top of other windows.

WORM (Write Once Read Many)
A compact disk optical storage technology that enables data to be written permanently to the optical platter. Data can be accessed repeatedly but not overwritten.

WWW (World-Wide Web)
The World-Wide Web (The Web) is a distributed information retrieval system on the Internet. Information is presented in hypertext objects using HTML Links to other Web servers or information pages. The information pages are specified as URLs. The Web originated from the CERN High-Energy Physics laboratories in Geneva, Switzerland. A client application is required, like Mosaic, for browsing information on Web servers.

WYSIWYG (What You See Is What You Get)
A representation of data on a monitor such that when printed, it is an exact facsimile of what appeared on the screen.

X Window System
Distributed, network-transparent, device-independent, multitasking windowing and graphics system originally developed by MIT for communication between X terminals and UNIX workstations.

X11R5 (X Window System Release 5)
Version 11, release 5 of the X protocol, it is a hierarchial windowing system developed at MIT that is network-transparent, and architecture-independent.

X11R6 (X Window System Release 6)
This is Version 11, release 6 of the X protocol, and is the latest version of the X Window protocol. See X11R5.

An established CCITT standard that defines the packet format for data transfers in a public data network. Frame relay is similar but requires less control information in each packet. Many establishments have X.25 networks in place that provide remote terminal access. These networks can be used for other types of data, including IP, DECnet and XNS.

A CCITT recommendation specifying an OSI standard for electronic mail transfer.

The X/Open Company, Ltd. is an independent international organization promoting open, multivendor application environments. It is, perhaps, best known for its XPG. Recently Novell transferred ownership of the UNIX trademark from USL to X/Open.

One of the original file transfer protocols that uses 128 byte packets.

XPG (X/Open Portability Guide)
A comprehensive set of voluntary APIs, protocols and other specifications designed to promote open, interoperable computing. XPG4 is the current version of this multivolume document.

An file transfer protocol that improved upon XMODEM and uses 1 Kb packets. See ZMODEM.

A file-transfer protocol that improved upon YMODEM. When a ZMODEM file transfer fails, the retransmission can pick up with the last successfully transferred packet, rather than needing to retransmit the entire file. simile of what appeared on the screen.