O

Object (computer/Windows)
In programming, elements combining data (properties) and behavior (methods) in a single container of code called an object. Objects inherit their properties and methods from the classes above them in the hierarchy and can modify these properties and methods to suit their own purposes. The code container may be part of the language itself, or you may define your own objects in source code. In Microsoft Windows, any piece of information, created using a Windows-based application with object linking/embedding capabilities, that can be linked or embedded into another document.

Object Code (computer)
Code in machine-readable from that can be executed by the computer's CPU and operating system. This code is usually linked with libraries to create an executable file.

Object Graphics (computer)
Images produced by turning on and off pixels by plotting vectors (points) that define lines and geometric shapes (such as circles, rectangles, ellipses, Bezier curves, and trapezoids). These plots are actually mathematically computed formulas called algorithms, which form the basis of all object-oriented drawing programs (also called vector graphics).

Object Linking and Embedding: OLE (computer/Windows)
In Microsoft Windows, a method to transfer and share information between applications.

Object Module (computer)
Machine language version of a program; it is produced by a compiler or assembler.

Object-Oriented Graphic (computer)
Graphic made up of distinct objects that can be individually modified.

Object Program (computer)
Output of a translating program, such as an assembler or a compiler, which converts a source program written in one language into another language, such as machine language, capable of being executed on a given computer. The output may be in one of several forms. It may be in an intermediate language, needing further translating; it may be relocate-able, in which data and program references are still expressed relative to a base address; or it may be absolute, where all linkages between elements have been made, and absolute address assignments established, so that the program is ready to be executed.

Object Programmer (computer)
Programmer that translates a program from one computer language into another.

Objective Time (A/V)
Also called clock time: the time as measured by the clock.

OCR (computer)
Optical Character Recognition - the machine recognition of printed characters. OCR systems can recognise many different kinds of special OCR fonts, as well as typewriter and computer-printed characters. Advanced OCR systems can recognise hand printing.

Octal Numbering System (computer)
System in which numbers are represented as linear combinations of powers of 8 (in comparison to binary with linear combinations of powers of 2, and hexadecimal with linear combinations of powers of 16).

Octave (A/V, Music)
In music, the grouping of a series of notes consisting of 13 semitones; the last note of an octave is twice the frequency of the first. In Western music, octaves begin and end with the same note letter and are divided into 8 pitches (CDEFGABC, in the C-major scale) or tones. These pitches have five additional half steps (semitones: A#, C#, D#, F#, G#) added to create the chromatic scale.

OEM (communications, computer)
Original Equipment Manufacturer - a manufacturer that sells equipment to a reseller. The term is also loosely used to refer to the reseller, as well. OEM customers typically purchase hardware from a manufacturer and resell it under their own brand names. They may combine units from several vendors as well as add software. OEM and VAR are often used synonymously (VAR = value added re-seller).

OEM Text (computer/Windows)
Format used by the Windows Clipboard when moving text into a non-Windows application. In this format, high-bit characters in the ANSI eight-bit set are translated to their equivalents in the IBM PC Character Set.

Office Automation (computer)
A term from the 1980’s defining the integration of all information functions in the office, including word processing, data processing, electronic mail, graphics, and desktop publishing. All traditional office functions are candidates for integration into an automated system. Office Automation may be a "wish" rather than reality since O/A has not yet been realised in most offices. Office Automation may have become a joke in the vernacular since most "automating" devices (personal computers, desktop publishing, laser printers, etc.) have actually increased paper burden. The irony of the Office of the Future, is that, once everyone has all the technology to implement it properly, they probably will not need the office, at all.

Off-Hook (communications)
State of a telephone line that allows dialling and transmission but prohibits incoming calls from being answered. The term goes back to the days when a telephone handset was lifted off of a hook (contrast with on-hook).

Off-Line (A/V, communications, computer)
Not connected to or not installed in the computer. Even if a terminal, printer, or other device is physically connected to the computer, it is still offline if it is not turned on, or not in ready mode. Disks and Tapes stored in a Library are considered to be "offline".

Term used in A/V to describe "rough cut" or rough draft of a videotape. In DTV, an off-line edit is used to create the final edit decision list (EDL) for the final, on-line edit.

Off-Set (computer/microelectronics)
Change in input voltage required to produce a zero output voltage in a linear amplifier circuit. In digital circuits, it is the dc voltage on which a signal is impressed.

Number of bytes from a reference point, usually the beginning of a file, to the particular byte of interest. When used for location, the first byte in a file is always 0. In MIDI terminology, offset is the time difference between 2 events, applied to SMPTE time code.

Off-Set Lithography (computer/printing)
Printing technique in which the image is offset from the printing plate onto a rubber blanket, and from there to the paper.

Off-Screen Buffer (computer, M/M)
Area in memory reserved for the preparation of Multimedia Movie Player images before they are displayed. The off-screen buffer improves the speed of operation of the application. The process of building the off-screen buffer data is called pre-imaging.

Ohm's Law (communications, computer)
Relationship of dc current first described by Georg Simon Ohm in 1827, based on his experiments with metallic conductors. The direct current flowing in an electrical circuit is directly proportional to voltage applied to the circuit. The constant of proportionality "r” - the electrical resistance, is given by the following equation, in which "V" is the applied voltage and "I" is the current: V = IR. Since 1827, numerous deviations, from the simple linear relationship, have been discovered.

Ohmmeter (communications, computer)
Small, portable instrument using a microammeter and associated circuitry to measure resistance by the voltmeter-ammeter method. Additional circuits are usually included to measure alternating and direct-current volts and amperes, and the instrument is called a volt-ohm-milliammeter, or multimeter.

OLE (computer/Windows)
Object Linking and Embedding. OLE is a Windows protocol developed by Microsoft Corporation. It provides for the creation of compound documents in which elements of a document, in an OLE client application, are created and edited (embedded) by or linked to a file (linking) in another application acting as an OLE server. Applications such as Word for Windows and Excel may act as either OLE clients or servers. Applets such as Media Player and Microsoft Draw and Chart are OLE servers only. OLE is an extension of the Windows Dynamic Data Exchange (DDE). OLE 1.0 accommodates BMP, DIB, and WMF formats for graphic images.

OLTP (computer)
Abbreviation for On Line Transaction Processing.

Omnidirectional (A/V, communications)
Meaning in all directions. An omnidirectional antenna picks up signals in all directions. An omnidirectional microphone responds equally to sound waves hitting it from all directions. Most omnidirectional microphones are characterized by a rounded cylindrical or hemispherical shape.

ONA (communications, computer)
Open Network Architecture: FCC (Federal Communications Commission) plan that allows users and competing enhanced service providers (ESPs) equal access to unbundled, basic telephone services. The Open Network Provision (ONP) is the European counterpart.

On-Demand Report (computer)
Report that provides information in response to an unscheduled demand from a user.

One-Level Memory (computer)
Computer memories in which all stored items are accessed by a uniform mechanism. In computer systems that possess such a memory, the programmer is relieved from considerations of data residence, and does not have to be concerned with I/O manipulations to access data that is stored on auxiliary memory devices.

On-Line (A/V, computer)
Device that is ready to operate. A printer can be attached, turned on, yet still not be online if the ONLINE light is out. Pressing the ONLINE button can bring it back online. In video production, a term describing final step in the editing process that creates the master videotape for duplication.

On-Line Editing (A/V, computer)
Audio/Visual term for final editing, using the original master tapes to produce a finished program, usually associated with a more costly, high-quality computer editing system.

Opacity (computer/printing)
Material's lack of transparency; for printing ink, the ability to hide or cover up the image or tone over which it is applied.

Op Code (computer)
Source statement (operating code) which generates machine code after assembly.

Open Architecture (communications, computer)
A system in which the specifications are made public in order to encourage third-party vendors to develop add-on products for it.

Open Circuit (computer/microelectronics)
Condition in an electric circuit in which there is no path for current between two points: examples include a broken wire, or a switch in the OPEN, or OFF position. Open circuit voltage is the difference between two points when a branch (current path) between them is open circuited. Open-circuit voltage is measured by a voltmeter (very high resistance - theoretically infinite).

Open Data-link Interface: ODI (communications, computer)
Local Area Network term, it was an API (application program interface) developed by Novell for LAN adapter drivers. ODI made it easier to use a NOS (network operating system) with various LAN adapters and allows multiple protocol stacks in the same host.

Opens (A/V, production, M/M)
Musical introductions (cues) at the beginning or in particular sections of a video production used to identify or emphasis new subject matter.

Open Set (A/V)
Set constructed of non-continuous scenery: large open spaces between main groupings.

Open System (communications, computer)
Vendor-independent system that is designed to interconnect with a variety of products that are commonly available. It implies that standards for such a system are determined from a consensus of interested parties rather than one or two vendors.

Open System Interconnection: OSI (communications)
Set of communications protocols defined by International Standards Organization (ISO).

Operand (computer)
One of the variables or constants upon which an operator acts. In 1+2 = 3, both 1 and 2 are operands; + and = are the operators. An operand is the entity on which operations are performed. In a typical computer, an instruction will specify an operation such as FETCH, ADD, MOVE, MULTIPLY, EDIT, etc. It will also usually specify one or more operands. The operands are the data items that will be fetched, added, moved, etc.

Operating Light Level (A/V)
Amount of light needed by the camera to produce a video signal. Most traditional, analog, colour cameras need from 100 to 250 foot-candles of illumination for optimal performance.

Operating System (computer)
Set of programs to control and coordinate the operation of hardware and software in a computer system. O/S typically consist of two programs. Control programs direct the execution of user application programs, and support programs. They also supervise the locations, storage and retrieval of data (including input and output to various peripherals) and allocate the resources of the computer system to the different tasks entered into the system. Processing programs include application programs, utility programs, system diagnostics; and language translators, such as compilers and interpreters. There are seven types of operating systems: Multiprogramming, Multiprocessing, Networking, Real-time, Serial (or batch), Single User, and Time Sharing.

Operating Research (computer)
Application of scientific methods and techniques to decision-making problems. A decision-making problem occurs where there are two or more alternative courses of action, each of which leads to a different and sometimes unknown end result. Operations research is also used to maximize the utility of limited resources. The objective is to select the best alternative, that is, the one leading to the best result. Some examples of decision-making problem solving are: linear programming model; networking model; Stochastic Processing including queuing theory, simulation, decision trees.

Operator (computer/mathematics)
Keyword or reserved symbol that acts on a single variable, otherwise on two variables, to produce a result. Operators may be conventional such as +, - (difference), /, and * (multiply) or the logical operators such as And or Not. When applied to a single variable in a statement, the unary minus (-) inverts sign from - to +, or + to -.

Optical Axis (communications/photonics)
Central axis of an optical system, along which the light propagates; the various optical elements are situated one after the other along the optical axis.

Optical Bistability (communications, computer/photonics)
Phenomenon in which an optical device can exist in either of two stable states. Optical bistability is an expanding field of research because of its application to all-optical logic. A bistable optical device can function as a variety of logic devices. It can have two stable output states: "0" and "1", for the same input. Therefore, it can serve as an optical memory element. Under slightly modified operating conditions, the same device can exhibit the optical transistor characteristic. Bistable devices will revolutionize optical processing, switching and computing. All-optical systems, where the transmission of information as signals impressed on light beams travelling through optical fibres, is replacing electrical transmission over copper cables. For very fast transmission systems, for example, (that can be transmitting a multiplexed composite of thousands of slow speed electrical signals), optical pulsing is considered much superior to traditional electronic systems. It is far easier to generate and transmit picosecond (1 trillionth) and femtosecond (1 quadrillionth) optical pulses than electrical pulses. Although any information processing and transmission system is likely to have electrical parts, especially for powering the light-emitting lasers and diodes, and interfacing to the end-user, the capability of sub-picosecond switching appears unique to the optical part of such a system.

Optical Character Reader (computer)
OCR may be defined as the high-speed process of converting machine (typewritten or printed) or hand-printed numerals, letters, and symbols into computer-processable information by an optical scanning system. Before data from an OCR document can be converted into machine representation, it has to pass through three major OCR subsystems: and electro-optical converter, a preprocessor, and a recognition logic system.

Optical Communications (communications, computer/photonics)
Transmission of information (voice, data, video) by light. An information-carrying light wave signal originates in a transmitter, passes through an optical channel, and enters a receiver which reconstruct the original information. The ensemble of these three items constitutes an optical communications system. Optical communications is one of the most advanced forms of communications by electromagnetic waves. Light waves are generally understood to occupy the part of the electromagnetic spectrum with wavelengths in the range of 0.2 to 100 micrometers (millionths of a meter). The advantages sought in using light waves instead of electromagnetic waves with longer wavelengths can be categorized in three ways: (1) because of its short wavelength, light can be focused into narrower beams or confined in smaller waveguide (cable) than radiation of longer wavelengths; (2) the information-carrying capacity is much greater than that of longer-wavelength radiation; (3) the highest transparency for electromagnetic radiation achieved in any solid material is that of silica glass in the wavelength range of 1 to 2 micrometers - this transparency is orders of magnitude higher than any other solid material in any spectrum.

Optical Detectors (communications)
Devices that generate a signal when light is incident upon them. The signal may be one observed visually in reflected or transmitted light or it may be above the visible spectrum. One of the most common optical detectors (other than one's eyes) is photographic film. Detection is based on a photochemical process in particles embedded in the film. The light detectors used in the construction of optical isolators include light-dependent resistors (such as photocells), light-sensitive devices that generate a voltage without any electrical input (such as photovoltaic devices), light sensitive devices that switch from one state to another (such as photothyristors), and light-sensitive devices that modify a voltage or current (such as phototransistors, photodiodes, photodetector-amplifier combinations).

Optical Disk (computer/photonics)
Disk written and read by light. CDs, CD ROMs, VideoDiscs are optical disks that are recorded during fabrication and cannot be erased. WORM (write once read many) disks are optical disks that are recorded in the user's environment, but cannot be erased.

Erasable optical disks function like magnetic disks and can be rewritten over and over again. In the late 1980s, many erasable optical disks were introduced that use magneto-optic, dye polymer and phase change recording technologies. Throughout the 1990s, erasable optical disks became the alternative to magnetic disk. Optical disk storage capacities are greater than their magnetic disk counterparts, and optical technology could eventually replace all magnetic tape and disk media. Lasers can be moved electronically and could be built into a whole new breed of storage device that does not spin and move mechanical arms, which would have a dramatic impact on future computer systems.

Optical Emitters (communications/photonics)
Most commonly selected optical emitter is the gallium arsenide light-emitting diode (LED), which emits in the infrared or near-infrared regions of the spectrum. The typical wavelength of the emission is 850 nm (nanometers or billionths of a meter). The LED is extremely small (transistor chip) and provides extremely fast infrared light pulses.

Optical Fibre (communications/photonics)
Thin filament of glass or other transparent material through which a signal-encoded light beam may be transmitted by means of total internal reflection.

Optical Fiber Communications
For glass fibres to become useful light waveguide, transparency and the control of signal distortion are fundamental to its success. Painstaking purification of conventional multi-component glasses, notable sodium borosilicates, before drawing them into fibre from the molten phase, has resulted in light guides which attenuate a light wave at 850 nanometers (billionths of a meter) wavelength by no more that 60 to 70% in 10 kilometres. Glass rods made by a special process and consisting almost entirely of silica can be pulled into fibre at temperatures approaching 2,000 degrees Celsius, and produce light guides that attenuate light at 850 nm by 40 to 50% in 10 kilometre, and light at 1550 nm by as little as 5% in 100 kilometres. Single mode fibre cables can maintain high-quality signal carrying without regeneration for thousands of kilometres. Low cost, Multi-mode fibre cables, for use in a building cabling system, for example, can maintain high-quality signal carrying without any noticeable degradation for up to 2 kilometres.

Optical Isolators (communications/photonics)
Very small four-terminal electronic circuit elements that include in an integral package a light emitter, a light detector and, in some devices, solid-state electronic circuits.

Optical Mark Readers (computer)
In optical mark reading, information is read as a series of marks on a sheet of paper, which are divided into a number of separate mark response positions. Each separate response position is then interpreted by the computer to have a specific meaning.

Optical Modulators (communications/photonics)
Devices that can vary some property of a light beam. The direction of the beam may be scanned as in an optical deflector, or the phase of frequency of an optical wave may be modulated. Most often, however, the intensity of the light is modulated. Variations of optical modulators are: electrooptic effect; electrooptic intensity modulation; acoustoopic modulation and deflection; optical waveguide, wave division multiplexing, and dense wave division multiplexing.

Optical Path (communications/photonics)
Distance a ray of light traverses, measured in wavelengths: takes into account the changes of the refractive index (changes of the wavelength).

Optical Pattern Recognition (computer/photonics)
Device used for the identification of a pattern by means of optical processing.

Optical Phase Conjugation (computer/photonics)
Generation of a light wave that retraces the propagation of an input wave (in reverse).

Optical Read Only Memory (computer)
An optical memory that can be read, but not written to, by the user.

Optical Receivers (communications/photonics)
Photodetectors are designed to capture light in a reverse-biased junction where it generates electron-hole pairs. The electrical carriers are swept out by the internal electrical field and induce a photocurrent in the external circuit. The minimum light level required for correct reconstruction of any information is limited by current superimposed on the signal photocurrent in subsequent regenerative stages. A photodiode receiver, if it collects 100 nanowatts (100 billionth) of signal light, can reconstruct a digital message of 100 gigabits per second (100 billion).

Optical Scanner (computer/scanner)
Input device that reads characters and images into the computer that are printed or painted on a paper form. The scanner does not recognize the data it is reading. Page recognition and image processing software do the actual recognition.

Optical Sound Track (A/V)
Variations of black and white patterns, photographed on the film and converted into electrical impulses by an exciter lamp and a photoelectric cell.

Optical Transfer Function (communications/photonics)
Effect of an optical (linear, shift invariant) system on a beam of light passing through it, described in the frequency domain: (Fourier transform of system's point spread function).

Optical Transmitters (communications/photonics)
Preferred sources for use in optical communications systems are semiconductor diodes which generate light in forward-biased operation. The simplest device is the light-emitting diode which radiates in all directions from a fluorescent area located in the diode junctions. Since fiber cables accept only light entering the core at a small angle with respect to the axis, a very small part of the light radiated from a light-emitting diode can be controlled, captured, and transmitting on the fiber cable. In a semiconductor laser, two ends of the junction plane are furnished with mirror surfaces which form an optical resonator and enhance the light bouncing back and forth between the mirrors by stimulated emission. A large percentage of the light can be captured and transmitted.

Optical Viewfinder (A/V)
Viewing device that uses and auxiliary lens rather than the miniature TV monitor, within camcorders. No playback of previous-recorded video is view-able with optical viewfinders.

Optimizing (computer/Windows)
Process of maximizing the speed and capacity of Windows with the user's system.

Optimization (computer)
In general terms, the efforts and processing making a decision, a design, or a system, as perfect, effective, or functional as possible. Formal optimization theory encompasses the specific methodology, techniques, and procedures used to decide on the one specific solution in a defined set of possible alternatives that will best satisfy the criterion.

Option Button (computer)
The original term (now "radio button") in CUA specification. They are circular control objects; the center is filled when selected. If grouped, only one button may be picked. In Windows, a common dialog box element. Option buttons present a set of mutually exclusive choices. The selection option is marked by a round dark dot in a circle.

Optoelectronics (microelectronics/photonics)
Merging of light/electronics technologies, as in optical fiber communications systems.

Optoelectronic Integrated Circuit (microelectronics/photonics)
Integrated circuit combining electronic logic and optical interconnection devices.

OR (computer/microelectronics)
Logic operation used to identify the operation wherein two or more true "1" inputs only add to one true "1" output. Only one input needs to be "true" to produce a "true" output. The graphical symbol for "OR" is a plus sign (+).

Orange Book (computer)
Philips Orange Book specification for CD-WO, Write Once Compact Disc, or CD Drives.

Orphan (computer/Windows)
In word processing, a word that is left all by itself on a line. In Microsoft Windows terminology, a member of a mirror set or a stripe set with parity that has failed in a severe manner, such as a loss of power or a complete head crash. When this happens, the fault-tolerance driver determines that it can no longer use the orphaned member and directs all new reads and writes to the remaining members of the fault-tolerance volume.

Oscillator (A/V, communications, computer)
Electronic circuit that converts energy from a direct-current source into a periodically varying electrical output, generating a continuous series of waves, at a constant frequency. Oscillators are used to create carrier signals and, in sound synthesis, modulation signals. Various types of oscillators include: bridge oscillator; crystal; integrated; heterodyne; microwave, phase-shift, and VHF oscillators (very-high-frequency).

Oscilloscope (A/V, communications, computer)
Electronic instrument which produces a luminous plot on a fluorescent screen showing the relationship of two or more variables. In most cases, it is an orthogonal (x,y) plot with the horizontal axis being a linear function of time. The vertical axis is normally a linear function of voltage at the signal input terminal of the instrument.

OSI (communications, computer)
Open System Interconnection - reference model defined by ISO (International Standards Organization) for worldwide communications. It defines a framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station, and back up the hierarchy. Similar functionality exists in all communications networks; however, existing non-OSI systems often incorporate two or three layers into one. Most vendors have agreed to support the OSI model in one form or another.

OSI Layers (communications)
OSI Layers are as follows (in reverse numeric order as you would enter from a computer)

#07 Application - Layer 7
Defines the rules for gaining entrance into the communications system. Programs communicate with other programs through this layer.

#06 Presentation - Layer 6
Negotiates and manages the way data is represented and encoded. Provides a common denominator for transferring data from different systems (ASCII, EBCDIC, Binary, etc.).

#05 Session - Layer 5
Coordination of communications in an orderly manner. For example, it marks significant parts of the transmitted data to ensure that the entire message is received properly.

#04 Transport - Layer 4
End-to-End validity and integrity of the transmission. OSI transport services include layers 1 through 4, which are collectively responsible for getting the bits from the sending station to the receiving station.

#03 Network - Layer 3
Route establishment between the sending and receiving stations. For example, this layer is the switching function of the dial-up telephone system.

#02 Data Link - Layer 2
Responsible for Node to Node validity and integrity of the transmission.

#01 Physical - Layer 1
Defines the functional characteristics for passing data bits onto and receiving them from the connecting medium. For example, it includes the request to send (RTS) and the clear to send (CTS) signals in an RS-232 environment, as well as time division multiplexing (TDM) in an ISDN environment. Note that electrical and mechanical characteristics define the interface between OSI environments and the connecting transmission medium.

OS/2 (computer)
An old Operating System, 16 bit and 32-bit, from IBM, for personal computers.

OTF Syntheses (microelectronics/photonics)
Realisation of an optical system with a predefined Optical Transfer Function; usually accomplished by means of a hologram.

Outbound Band (communications, computer)
Type of local area networking configuration, whereby a frequency band carries information from the head-end of the LAN (at the File Server) to the LAN nodes.

Output (computer)
Raw data that has been processed into usable information; also, an output device, such as a printer, that makes processed information available for use.

Outro (A/V, music)
Musical ending (finale) in a video production. The complement to intro.

Outsourcing (computer)
Term that came into popularity in the 1990's in all fields but particularly so in the computer industry to describe computing services normally provided by internal company sources (resources) being handed over to outside specialists including: management information systems (MIS), administrative services, training, and also technical support. It has been estimated that, by the year 2005, over 75% of the computing expertise used by companies will be "outsourced" under contract to companies or individuals.

Outtakes (A/V)
Term used in Audio/Visual production to describe the shots that are edited out of the final (airtime) videotape of a news story: discarded, unused video scenes.

Overdeviation (A/V)
Term used in Audio/Visual production to describe a black fringing effect in an overly bright picture or overly saturated color, caused by an excess of chroma or video level that is too high for the tape, camera, or recorder to handle (colloquially, also called bearding).

Over Dub (A/V)
In audio recording, a new sound track created to replace a pre-recorded track.

Overflow Error (computer)
In database management an error that occurs when information cannot fit within the designated database field: also it can be a machine code error within the computer, when code is being compiled in the ALU (Arithmetic Logic Unit - or - Shift Registers).

Overglaze (computer/microelectronics)
Glass compound in low-melting, vitreous form, used as a coating to passivate thick film resistors and other mechanical protection.

Overhead (computer)
Time that a computer system spends doing computations that do not contribute directly to the progress of any user tasks in the system.

Overhead Projector (computer)
Projector for Acetate Transparencies approximately 8.5" x 11" (paper size) that reflects and projects the transparency images onto a wall or screen. A peripheral device can be used that is plugged into a computer and placed onto the projector image surface (liquid crystal display panel), that then projects graphics being generated from the computer.

Overlap (computer/microelectronics)
Contact area between a film resistor and film conductor.

Overlay (computer/printing)
When a section of computer code is loaded into a central memory area that was previously allocated to another section of the same executing program, the process is called overlaying, and the loaded section of code is called an overlay. An overlay may contain instructions or data, or a combination of instructions and data.

In printing terms, transparent paper or film placed over artwork to protect it from damage, to indicate instructions to the printer, or to illustrate the breakdown of color in mechanical color separations (can have a number of overlays, showing color separations).

Overprint (computer/printing)
Object that prints on top of other colors; the opposite of a knockout.

Oversampling (A/V, communications)
Term describing conversion of analog audio signals to digital form using a sampling rate much higher than theoretically required to reproduce the highest frequency (a sampling rate of twice the highest frequency to be converted). Oversampling is usually expressed as a multiple (16x, 64x) of the required sampling rate.

Overstrike (computer)
When typing (on-screen view), to write over existing characters or text: also to cross-out.

Over-The-Shoulder Shot (A/V)
Audio/Visual production term for a Camera that looks over a person's shoulder (with the shoulder and the back of head in the shot) at another person.

Overwrite (computer)
To type over existing text, characters, data, on the screen.

Owner Display (computer/Windows)
Format option available in Clipboard Viewer. In owner display, the contents of the Clipboard are displayed the way they were received from the sending application.