Occupational Safety and Health Act (OSHA) - The United States (U.S.) federal statute creating the Occupational Safety and Health Administration.

octet - A data unit of eight bits. See also byte.

off-axis - 1. Not in a straight line. 2. A state of an optical system in which the optical axis of the aperture does not coincide with the mechanical center of the aperture.

offload - Advanced error checking performed by a network interface card.

offset - Degree to which the cable or conduit changes direction.

offset (frequency) - The difference between the frequency of source and reference frequencies.

Ohm's law - The mathematical relationship among electric current, resistance, and voltage. The voltage in volts is equal to the current in amperes multiplied by the resistance in ohms.

ohmmeter - A device used to measure voltage and resistance.

OmniCIass - Construction Classification System (OCCS) A multitable system for organizing information used by the architectural, engineering, and construction industry. The OCCS is the basis for deriving relational applications and will support and empower the transfer and use of information in the construction marketplace, ultimately serving all participants who work to sustain the built environment throughout the entire life cycle of a facility. (CSI)

omnidirectional antenna - An antenna characterized by a broad coverage zone that radiates signals in all direction equally. See also directional antenna and unidirectional antenna.

omnidirectional - Radiating in all directions for the source signal.

open - A condition on a conductor that affects continuity.

open office - A floor space division provided by furniture, movable partitions, or other means instead of by building walls. (TIA)

open office cabling - The cabling that distributes from the horizontal cross-connect (floor distributor) to the open office area utilizing a consolidation point or multi-user telecommunications outlet.

Open Systems Interconnection (OSI) - Reference Model A seven-layer architecture developed by the Intemational Organization for Standardization that has served as a foundation for the development of many standards for network systems communications. The seven layers are physical, data link, network, transport, session, presentation, and application.

open wire - Typically, 19 AWG [0.91 mm (0.036 in)] noninsulated wire that consists of copper or copper and steel used in aerial plant construction.

operating system (OS) - Software that controls the execution of all programs and the utilization of resources on a device such as a personal computer.

optical character recognition (OCR) - A method of scanning documents and converting the image into a text document that can be searched and indexed.

optical fiber - A transmission media using a thin filament of glass or plastic to transmit pulse light signals. Its bandwidth is higher than copper and not subject to electromagnetic interference. The optical fiber consists of a central core (glass or plastic) and an outer cladding. See also plastic optical fiber.

optical fiber cable - Cable made up of one or more strands of glass consisting of a central core and outer cladding (optical fibers), strength members, and an outer jacket.

optical fiber cladding - See cladding.

optical fiber connector - A device attached to the end of an optical fiber for the purpose of mating the fiber to a source, receiver, or to another fiber through an optical adapter.

optical fiber core - See core.

optical fiber duplex adapter - A mechanical cable termination device designed to align and join two duplex optical fiber connectors.

optical fiber duplex connection - A mated assembly of two duplex connectors and a duplex adapter. (TIA)

optical fiber duplex connector - A mechanical cable termination device designed to transfer optical power between two pairs of optical fibers.

optical fiber flashlight - A device that generates safe visible light (e.g., light-emitting diode) for verifying continuity of optical fiber with the naked eye.

optical field of view - The area visible through the lens of an optical instrument.

optical network terminal (ONT) - The single network interface device for voice, data, and video services delivered to the premises/line unit.

optical power ground wire (OPGW) - A special electrical conductor containing embedded optical fibers used in place of a standard static (lightning protection) conductor used at the top of electrical transmission structures. These resilient cables allow electrical transmission corridors also to serve as optical fiber communication routes. Also called optical ground wire.

optical power meter - Test equipment that measures in dBm the strength of a light wave over an optical fiber cable.

optical time domain reflectometer (OTDR) - An instrument that measures transmission characteristics of optical fiber by measuring the backscatter and reflection of injected light as a function of time. Used to measure attenuation of optical fiber, splices, connectors, and locate faults.

optoelectronics - The components or circuitry used to perform the necessary conversions between light-based signaling and electricity-based signaling.

order of magnitude - An expression where the upper value is 10 times larger than the lower value.

"or equal" - Used to identify a level of quality or feature(s) of a specific product or assembly that can be substituted but must be equivalent to the specified product in every way. Better phrases are "or as approved" or "or approved substitute."

organizational network - An interconnected system of computers, peripheral devices, and software designed to enable the transfer of all types of messages between users and devices.

orthogonal frequency division multiplexing (OFDM) - A technique whereby a wide frequency band is split into a number of narrow frequency bands. Data is inverse multiplexed across the subchannels. Used in IEEE 802.11a and 802.11g networks.

outbound - Connections from a network to an external device. Also called outgoing.

outer protection - An outer layer of material, composed of armored wire or metallic tape, covering the sheath of the cable.

outlet box (telecommunications) - A metallic or nonmetallic box mounted within a floor, wall, or ceiling and used to hold telecommunications outlets/connectors or transition device. (TIA)

outlet cable (OC) - A cable placed in a residential unit extending directly between the telecommunications outlet/connector and the distribution device. (TIA)

outlet/connector (telecommunications) - A connecting device in the work area on which horizontal cable or outlet cable terminates. (TIA)

outside plant (OSP) - Telecommunications inf,rastructure designed for installation exterior to buildings and is typically routed into the entrance facility. (TIA)

outside plant (OSP) cables - Typically used outside of a building but also may be routed into the entrance facility.

overbuild - Customer-owned outside plant facilities placed in conjunction with existing outside plant of a locally owned or competitive company.

overcurrent - Any level of electrical current that is higher than the rating of the cabling or device.

overfill - The energy around a receive antenna that is lost due to its being outside the surface where it can be captured.

overfilled launch - The condition when the cladding of an optical fiber is completely filled with light.

overlashing - The practice of lashing a new cable over an existing aerial support strand and cable bundle.

overvoltage - An increase in voltage similar to a surge but for a longer period of time over 2.5 seconds. (Neneveld's Pocket Guide to Residential Technology Terms and Definitions)