object

n. 1. Short for object code (machine-readable code). 2. In object-oriented programming, a variable comprising both routines and data that is treated as a discrete entity. See also abstract data type, module (definition 1), object-oriented programming. 3. In graphics, a distinct entity. For example, a bouncing ball might be an object in a graphics program.

object model

n. 1. The structural foundation for an object-oriented language, such as C++. This foundation includes such principles as abstraction, concurrency, encapsulation, hierarchy, persistence, polymorphism, and typing. See also abstract data type, object (definition 2), object-oriented programming, polymorphism. 2. The structural foundation for an object-oriented design. See also object-oriented design. 3. The structural foundation for an object-oriented application.

object-oriented

adj. Of, pertaining to, or being a system or language that supports the use of objects. See also object (definition 2).

object-oriented graphics

n. Computer graphics that are based on the use of graphics primitives, such as lines, curves, circles, and squares. Object-oriented graphics, used in applications such as computer-aided design and drawing and illustration programs, describe an image mathematically as a set of instructions for creating the objects in the image. This approach contrasts with the use of bitmapped graphics, in which a graphic is represented as a group of black-and-white or colored dots arranged in a certain pattern. Object-oriented graphics enable the user to manipulate objects as units. Because objects are described mathematically, object-oriented graphics can be layered, rotated, and magnified relatively easily. Also called structured graphics. See also graphics primitive. Compare bitmapped graphics, paint program.

object-oriented operating system

n. An operating system based on objects and designed in a way that facilitates software development by third parties, using an object-oriented design. See also object (definition 2), object-oriented design.

OC3

n. Short for optical carrier 3. One of several optical signal circuits used in the SONET high-speed fiber-optic data transmission system. OC3 carries a signal of 155.52 Mbps, the minimum transmission speed for which SONET and the European standard, SDH, are fully interoperable. See also SONET.

octal

n. The base-8 number system consisting of the digits 0 through 7, from the Latin octo, meaning "eight." The octal system is used in programming as a compact means of representing binary numbers. See Appendix E. See also base (definition 2).

octet

n. A unit of data that consists of exactly 8 bits, regardless of the number of bits a computer uses to represent a small amount of information such as a character. Compare byte.

OCX

n. Short for OLE custom control. A software module based on OLE and COM technologies and that, when called by an application, produces a control that adds some desired feature to the application. OCX technology is portable across platforms, works on both 16-bit and 32-bit operating systems, and can be used with applications. It is the successor to VBX (Visual Basic custom control) technology, which supported only Visual Basic applications, and is the basis for ActiveX controls. OCXs can be written in a variety of languages, although Visual C++ is most commonly used. Developed by Microsoft, OCX technology is covered in the 1996 OLE Controls specification (OCX 96). See also ActiveX controls, COM (definition 2), control (definition 2), OLE, VBX, Visual Basic.

ODBC

n. Acronym for open database connectivity. In the Microsoft WOSA structure, an interface providing a common language for Windows applications to gain access to a database on a network. See also WOSA.

office automation

n. The use of electronic and communications devices, such as computers, modems, and fax machines and any associated software, to perform office functions mechanically rather than manually.

offline

adj. 1. In reference to a computing device or a program, unable to communicate with or be controlled by a computer. Compare online (definition 1). 2. In reference to one or more computers, being disconnected from a network. Compare online (definition 2).

offline navigator

n. Software designed to download e-mail, Web pages, or newsgroup articles or postings from other online forums and save them locally to a disk, where they can be browsed without the user paying the cost of idle time while being connected to the Internet or an online information service. Also called offline reader.

offline reader

n. See offline navigator.

offload

vb. To assume part of the processing demand from another device. For example, some LAN-attached gateways can offload TCP/IP processing from the host machine, thereby freeing up significant processing capacity in the CPU. See also central processing unit, gateway, host, TCP/IP.

offset

n. In relative addressing methods, a number that tells how far from a starting point a particular item is located. See also relative address.

off-the-shelf

adj. Ready-to-use; packaged. The term can refer to hardware or software.

ohm

n. The unit of measure for electrical resistance. A resistance of 1 ohm will pass 1 ampere of current when a voltage of 1 volt is applied.

OLE

n. Acronym for object linking and embedding. A technology for transferring and sharing information among applications. When an object, such as an image file created with a paint program, is linked to a compound document, such as a spreadsheet or a document created with a word processing program, the document contains only a reference to the object; any changes made to the contents of a linked object will be seen in the compound document. When an object is embedded in a compound document, the document contains a copy of the object; any changes made to the contents of the original object will not be seen in the compound document unless the embedded object is updated.

online

adj. 1. In reference to a computing device or a program, activated and ready for operation; capable of communicating with or being controlled by a computer. Compare offline (definition 1). 2. In reference to one or more computers, connected to a network. Compare offline (definition 2). 3. In reference to a user, currently connected to the Internet, an online service, or a BBS or using a modem to connect to another modem. 4. In reference to a user, being able to connect to the Internet, an online service, or BBS by virtue of having an account that gives one access.

online community

n. 1. All users of the Internet and World Wide Web collectively. 2. A local community that places political forums online for the discussion of local government or issues of public concern. 3. Members of a specific newsgroup, mailing list, MUD, BBS, or other online forum or group. See also BBS (definition 1), mailing list, MUD, newsgroup.

online information service

n. A business that provides access to databases, file archives, conferences, chat groups, and other forms of information through dial-up, or dedicated communications links, or through the Internet. Most online information services also offer access to the Internet connections along with their own proprietary services. The largest consumer online information services in the United States are America Online, CompuServe, and The Microsoft Network.

online state

n. The state of a modem when it is communicating with another modem. Compare command state.

on the fly

adv. Doing a task or process as needed without suspending or disturbing normal operations. For example, it is often said that an HTML document can be edited on the fly because its content can be revised without the need to completely shut down or recreate the Web site on which it resides. See also HTML document, Web site.

open¹

adj. Of, pertaining to, or providing accessibility. For example, an open file is one that can be used because a program has issued an "open file" command to the operating system.

open²

vb. To make an object, such as a file, accessible.

open architecture

n. 1. Any computer or peripheral design that has published specifications. A published specification lets third parties develop add-on hardware for a computer or device. Compare closed architecture (definition 1). 2. A design that provides for expansion slots on the motherboard, thereby allowing the addition of boards to enhance or customize a system. Compare closed architecture (definition 2).

OpenDoc

n. An object-oriented application programming interface (API) that enables multiple independent programs (component software) on several platforms to work together on a single document (compound document). Similar to OLE, OpenDoc allows images, sound, video, other documents, and other files to be embedded or linked to the document. OpenDoc is supported by an alliance that includes Apple, IBM, the Object Management Group, and the X Consortium. See also application programming interface, component software. Compare ActiveX, OLE.

open file

n. A file that can be read from, written to, or both. A program must first open a file before the file's contents can be used, and it must close the file when done. See also open².

Open Financial Connectivity

n. The Microsoft specification for an interface between electronic banking services and Microsoft Money personal finance software. Acronym: OFC.

open standard

n. A publicly available set of specifications describing the characteristics of a hardware device or software program. Open standards are published to encourage interoperability and thereby help popularize new technologies. See also standard (definition 2).

open system

n. 1. In communications, a computer network designed to incorporate all devices--regardless of manufacturer or model--that can use the same communications facilities and protocols. 2. In reference to computer hardware or software, a system that can accept add-ons produced by third-party suppliers. See also open architecture (definition 1).

operating system

n. The software that controls the allocation and usage of hardware resources such as memory, central processing unit (CPU) time, disk space, and peripheral devices. The operating system is the foundation on which applications are built. Popular operating systems include Windows 95, Windows NT, Mac OS, and UNIX. Also called executive. Acronym: OS.

operation

n. 1. A specific action carried out by a computer in the process of executing a program. 2. In mathematics, an action performed on a set of entities that produces a new entity. Examples of mathematical operations are addition and subtraction.

optical character recognition

n. The process in which an electronic device examines printed characters on paper and determines their shapes by detecting patterns of dark and light. Once the scanner or reader has determined the shapes, character recognition methods--pattern matching with stored sets of characters--are used to translate the shapes into computer text. See also character recognition. Compare magnetic-ink character recognition. Acronym: OCR.

optical drive

n. A disk drive that reads and often can write data on optical (compact) discs. Examples of optical drives include CD-ROM drives and WORM disk drives. See also CD-ROM drive, compact disc, WORM.

optical fiber

n. A thin strand of transparent material used to carry optical signals. Optical fibers are constructed from special kinds of glass and plastic, and they are designed so that a beam of light introduced at one end will remain within the fiber, reflecting off the inner surfaces as it travels down the length of the fiber. Optical fibers are inexpensive, compact, and lightweight and are often packaged many hundred to a single cable. See also fiber optics.

optical recognition

n. See optical character recognition.

optimization

n. 1. In programming, the process of producing more efficient (smaller or faster) programs through selection and design of data structures, algorithms, and instruction sequences. 2. The process of a compiler or assembler in producing efficient executable code. See also optimizing compiler.

Option key

n. A key on Apple Macintosh keyboards that, when pressed in combination with another key, produces special characters--graphics, such as boxes; international characters, such as currency symbols; and special punctuation marks, such as en dashes and em dashes. The Option key serves a purpose similar to that of the Control key or the Alt key on IBM and compatible keyboards in that it changes the meaning of the key with which it is used.

Orange Book

n. 1. A U.S. Department of Defense standards document entitled "Trusted Computer System Evaluation Criteria, DOD standard 5200.28-STD, December, 1985," which defines a system of ratings from A1 (most secure) to D (least secure), indicating the ability of a computer system to protect sensitive information. Compare Red Book (definition 1). 2. A specifications book written by the Sony and Philips Corporations, covering the compact disc write-once formats (CD-R, PhotoCD). See also CD-R, ISO 9660, PhotoCD. Compare Green Book, Red Book (definition 2).

order¹

n. 1. In computing, the relative significance of a digit or byte. High-order refers to the most significant (usually leftmost) digit or byte; low-order refers to the least significant (usually rightmost) digit or byte. 2. The magnitude of a database in terms of the number of fields it contains. 3. The sequence in which arithmetic operations are performed.

order²

vb. To arrange in a sequence, such as alphabetic or numeric.

orientation

n. See landscape mode, portrait mode.

original equipment manufacturer

n. The maker of a piece of equipment. In making computers and related equipment, manufacturers of original equipment typically purchase components from other manufacturers of original equipment, integrate them into their own products, and then sell the products to the public. Compare value-added reseller. Acronym: OEM.

orphan

n. The first line of a paragraph printed alone at the bottom of a page or column of text, or the last line of a paragraph printed alone at the top of a page or column. Orphans are visually unattractive and thus undesirable in printed materials. Compare widow.

orphan file

n. A file that remains on a system after it has ceased to be of use. For example, a file may be created to support a particular application but may remain after the application has been removed.

OS/2

n. A protected-mode, virtual-memory, multitasking operating system for personal computers based on the Intel 80286, 80386, i486, and Pentium processors. OS/2 can run most MS-DOS applications and can read all MS-DOS disks. Important OS/2 subsystems include Presentation Manager, which provides a graphical user interface, and LAN Manager, which provides networking facilities. OS/2 was initially developed as a joint project of Microsoft and IBM but is now an IBM product. See also protected mode, virtual memory.

oscilloscope

n. A test and measurement instrument that provides a visual display for an electrical signal. Most commonly, oscilloscopes are used to create a display of voltage over time. Also called cathode-ray oscilloscope.

OSF

n. Acronym for Open Software Foundation. A nonprofit consortium of firms (including DEC, Hewlett-Packard, and IBM), formed in 1988, that promotes standards and specifications for programs operating under UNIX and licenses software (as source code) to its members. OSF's products include the Distributed Computing Environment, the graphical user interface Motif, and the OSF/1 operating system (a variant of UNIX).

OSI

n. See ISO/OSI model.

OSPF

n. Acronym for Open Shortest Path First. A routing protocol for IP networks, such as the Internet, that allows the router to calculate the shortest path to each node for sending messages. The router sends information on the nodes it is linked to, called link-state advertisements, to other routers on the network to accumulate link-state information to make its calculations. See also communications protocol, node (definition 2), path (definition 1), router.

Outbox

n. In many e-mail applications, the default mailbox where the program stores outgoing messages. See also e-mail¹ (definition 1), mailbox. Compare Inbox.

outline font

n. A font (type design) stored in a computer or printer as a set of outlines for drawing each of the alphabetic and other characters in a character set. Outline fonts are templates rather than actual patterns of dots and are scaled up or down to match a particular type size. Such fonts are most often used for printing, as is the case with most PostScript fonts on a PostScript-compatible laser printer and TrueType fonts. Compare bitmapped font, screen font, stroke font.

out-of-band signaling

n. Transmission of some signals, such as control information, on frequencies outside of the bandwidth available for voice or data transfer on a communications channel.

overlay¹

n. 1. A section of a program designed to reside on a designated storage device, such as a disk, and to be loaded into memory when needed, usually overwriting one or more overlays already in memory. Use of overlays allows large programs to fit into a limited amount of memory, but at the cost of speed. 2. A printed form positioned over a screen, tablet, or keyboard for identification of particular features. See also keyboard template.

overlay²

vb. 1. In computer graphics, to superimpose one graphic image over another. 2. In video, to superimpose a graphic image generated on a computer over video signals, either live or recorded.

overstrike

vb. To type or print one character directly over another so that the two occupy the same space on the page or screen.

overtype mode

n. See overwrite mode.

overwrite mode