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OA:
office automation.

object:
(1) In computer security, an entity to which access is controlled; for example, a file, a program, an area of main storage; data collected and maintained about a person. (2) In programming languages, a set of operations and data that store and retain the effect of the operations. Objects are implemented as packages or tasks in Ada, as "modules" in Modula-2, and as "objects" in Smalltalk. In object-oriented programming, an object is an instance corresponding to a class definition. (3) In artificial intelligence, a physical or conceptual entity that may have one or more attributes.

object code:
A final version of code prior to execution. An object program is made up of object code.

object language:
A target language for expressing object programs.

object module:
All or part of an object program sufficiently complete for linking. Assemblers and compilers usually produce object modules.

object-oriented:
Pertaining to a technique or to a programming language that supports objects, classes, and inheritance. Some authorities list the following requirements for object-oriented programming: information hiding or encapsulation, data abstraction, message passing, polymorphism, dynamic binding, and inheritance.

object-oriented language:
A programming language that supports object-oriented concepts; for example: Eiffel, Smalltalk, C++, Java.

object plane:
The imaginary plane in a scene that is focused onto the specified image plane by a lens.

object program:
A target program that, if necessary, must be linked, before it can be executed by a particular computer.

object reuse:
In computer security, the use of a data medium that once held one or more data objects to hold a new data object. For secure object reuse, scavenging must be prevented. To prevent scavenging, a system must either eliminate residual data or prevent reading without writing.

object type:
In object-oriented programming, a template for objects that defines the internal structure and the set of operations for instances of such objects.

obsoleting indication service:
A service that allows the originator to indicate to the recipient that one or more messages previously sent are now obsolete.

obscure:
To block the user's view of part or all of a displayed object with another; for example, to partially block one window with another.

occlude:
To block the initiation of actions or selections associated with a displayed object; for example, to prevent the activation of an option by covering it with a transparent window.

occlusion:
The property of an image whereby some potential content is blocked by other content. Such content may be blocked from access, but still be visible; for example: that part of a display window overlapped by another; the absence of an object in an image due to the presence of another object in the corresponding scene.

OCR:
optical character recognition.

octal:
(1) Characterized by a selection, choice, or condition that has eight possible different values or states. (2) Of a fixed-radix notation, having a radix of eight.

octal numeral:
A numeral in the octal system.

octal numeration system:
Synonym for octal system.

octal system:
The fixed-radix notation that uses the eight digits 0, 1, 2, 3, 4, 5, 6, and 7, a fixed radix of eight, and the lowest integral weight of 1; for example, in the octal system, the numeral 1750 represents 1 x 83 + 7 x 82 + 5 x 81 + 0 x 80 equivalent to the decimal numeral 968. Synonymous with octal numeration system.

octet:
A byte that consists of eight bits. Synonymous with 8-bit byte.

octree:
The expression of a three-dimensional object as a tree structure of octants, which are formed by recursively subdividing each nonhomogeneous octant until all octants are homogeneous (either full or empty) or until a predetermined cutoff depth is reached. The octree technique compresses the amount of stored data about a three-dimensional object. Contrast with quadtree. (Figure 46 - Octree).

ODC:
optical disk cartridge.

office automation (OA):
The integration of office activities by means of a data processing system. Office automation includes the processing and communication of text, images, voice, and video.

office automation system:
An information processing system used to integrate office activities.

offline:
Pertaining to the operation of a functional unit that may be connected, but is unable to interact with another functional unit. The other functional unit is usually senior in some respect.

offline storage:
Storage that is not under the control of a central processing unit.

offset track:
A track written at a nonstandard position on a floppy disk, as part of a method of copy protection.

OLAP:
online analytical processing.

one-address instruction:
An instruction that contains one address part; for example, an instruction to load the contents of storage location A. Synonymous with single-address instruction.

one-ahead addressing:
A method of implicit addressing in which the operands for an instruction are understood to be in the storage locations following the locations of the operands used for the last instruction executed.

one-beam overwrite:
A method in which the data is written using a laser beam by overwriting without prior erasing.

one-plus-one address instruction:
An instruction that contains two address parts, the second containing the address of the instruction to be executed next; for example, an instruction to load the contents of storage location A, then execute the instruction in storage location B.

ones complement:
The diminished radix complement in the binary system.

one-shot:
Synonym for monostable trigger circuit.

one-way cipher:
An irreversible function f from plaintext to ciphertext. It is computationally infeasible to systematically determine a plaintext message M from the ciphertext C=f(M).

one-way communication:
Data communication such that data are transferred only in one preassigned direction.

one-way encryption:
Synonym for irreversible encryption.

online:
(1) Pertaining to the operation of a functional unit when connected to and able to interact with another functional unit. The other functional unit is usually senior in some respect. An example is a personal computer connected to a computer network. (2) Pertaining to user access to a computer via a user terminal.

online analytical processing (OLAP):
Analytical processing by using a multidimensional view of data to analyze performance by product, region, market, over time and to move up and down the hierarchies of each dimension.

on-the-fly printer:
An impact printer in which the type band or type slugs do not stop moving during the impression time.

op code:
Synonym for operation code.

open-ended:
Pertaining to a process or system that can be augmented.

open guard:
A guard whose condition evaluates to TRUE.

open security environment:
An environment in which protection of data and resources from accidental or malicious acts is achieved through normal operational procedures.

open subroutine:
A subroutine that must be inserted at each place the subroutine is used in a program.

open system:
A system containing publicly defined interfaces and protocols to facilitate interoperability with other systems, perhaps of different design or manufacture. Contrast with closed system.

open systems interconnection (OSI):
The interconnection of open systems in accordance with ISO/IEC standards and ITU-T Recommendations for the exchange of data.

Open Systems Interconnection Reference Model (OSI-RM):
A model that describes the general principles of open systems interconnection and the network architecture resulting from those principles. (Figure 47 - The Open Systems Interconnection Reference Model).

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