LAP-BThe Data Link Layer protocol as specified by ITU-T Recommendation X.25 (1989).
LAP-DAbbreviation for link access procedure D. A link protocol used in ISDN.
large prime factorsSpecially constructed large prime numbers, viz., p1, p2, q1, and q2, each > 2100, where p1|p-1, p2|p+1, q1|q-1, and q2|q+1, where p and q are the private…
laser(LAY-zer) A device that concentrates light into an intense, narrow beam used to cut or destroy tissue.
laser chirpAn abrupt change of the center wavelength of a laser, caused by laser instability.
lateral offset lossIn fiber optics, a loss of optical power at a splice or connector, caused by a lateral, i.e.
LatticeThe regular periodic arrangement of atoms or molecules in a crystal of semiconductor material.
launch angleThe angle, with respect to the normal, at which a light ray emerges from a surface. 2.
launch numerical aperture (LNA)The numerical aperture of an optical system used to couple (launch) power into an optical fiber.
launching fiberAn optical fiber used in conjunction with a source to excite the modes of another fiber in a particular fashion.
lay lengthIn communications cables--including fiber-optic cables--having the transmission media wrapped helically around a central member, the longitudinal distance…
layerA thematic set of spatial data described and stored in an ArcStorm database or a LIBRARIAN map library.
layer entityAn active element within a layer. [T1.630-1999]
layer functionA part of the activity of the layer entities. [T1.627-1993]
layer interfaceThe boundary between two adjacent layers in the model. [T1.110-1987]
layer serviceA capability of the (N) layer and the layers beneath it, which is provided to (N + 1) layer entities, at the boundary between the (N) layer and the (N +…
layer service elementsAn indivisible component of the layer service made visible to the service user via layer service primitives. [T1.110-1987]
layer service primitivesA means for specifying in detail the adjacent layer interactions. [T1.110-1987]
layer user dataData transferred between corresponding entities on behalf of the upper layer or layer management entities for which they are providing services. [T1.
layered protocolThe protocol reference model defined by layered structures based on and using the terminology of ITU-T Recommendations X.200 and X.210.
layered systemA system in which components are grouped, i.e., layered, in a hierarchical arrangement, such that lower layers provide functions and services that support…
LBOAbbreviation for line buildout. Synonym building out.
LDAPA protocol for accessing directory information. LDAP or Lightweight Directory Access Protocol is used by browsers and email clients to look up email…
leaky bucket counterA counter that is incremented by one each time an event occurs and is decremented by a fixed value periodically. [T1.218-1991]
leaky modeIn an optical fiber, a mode having a field that decays monotonically for a finite distance in the transverse direction but becomes oscillatory everywhere…
leaky rayIn an optical fiber, a ray for which geometric optics would predict total internal reflection at the boundary between the core and the cladding, but which…
leap secondAn occasional adjustment of one second, added to, or subtracted from, Coordinated Universal Time (UTC) to bring it into approximate synchronism with UT1…
leased circuitDedicated common-carrier facilities and channel equipment used by a network to furnish exclusive private line service to a specific user or group of users.
Least PrivilegeThis principle requires that each subject in a system be granted the most restrictive set of privileges (or lowest clearance) needed for the performance…
least significant bitIn a binary code, the bit or bit position that is assigned to, or represents, the smallest quantity or increment that can be represented by the code.
left-hand (anti-clockwise) polarized waveAn elliptically or circularly polarized wave, in which the electric field vector, observed in the fixed plane, normal to the direction of propagation…
length indicator (LI)A six-bit field that defines message length and that is used to differentiate between message signal units, link status signal units, and fill-in signal…
LERG AssigneThe SP responsible for default routing functions associated with a pooled NXX code.
LERG™ Routing GuideThe Telcordiaî LERG⢠Routing Guide contains information about the local routing data obtained from the BIRRDS.
LevelThe number of values used in a card counting system. A level one counting system only uses +1 and -1, but a level two system would use +1, +2, -1 and -2…
level alignmentThe adjustment of transmission levels of single links and of links in tandem to prevent problems such as overloading of transmission subsystems.
level of protection[The] extent to which protective measures, techniques, and procedures must be applied to information systems (IS) and networks based on risk, threat…
libraryA collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species.
life cycleThe sequence of events from a given developmental stage in one generation to the same stage in the following generation.
LIFOLast In, First Out. See also "FIFO". A LIFO is usually called a "stack".
LightA pane of glass; a window, or a compartment of a window.
light penA stylus, usually hand-held, that contains a photodetector or light source, and that allows interaction with a computer through a specially designed…
lightnessThe brightness of an area subjectively judged relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting.
lightning down-conductorIn a lightning protection subsystem, the conductor connecting the air terminal or overhead ground wire to the earth electrode subsystem.
limited protectionA form of short-term communications security applied to the electromagnetic or acoustic transmission of unclassified information that warrants a degree of…
limiterA device in which the voltage or some other characteristic of the output signal is automatically prevented from exceeding a specified value.
limiter circuitA circuit of nonlinear elements that restricts the electrical excursion of a variable in accordance with specified criteria.
limitingAny process by which a specified characteristic (usually amplitude) of the output of a device is prevented from exceeding a predetermined value.
limits of interferenceIn radio transmission, the maximum permissible interference as specified in recommendations of the International Special Committee on Radio Interference…
line codeA code chosen for use within a communications system for transmission purposes.
line conditioning[The] elimination of unintentional signals or noise induced or conducted on a telecommunications or information system signal, power, control, indicator…
line conductionUnintentional signals or noise induced or conducted on a telecommunications or information system signal, power, control, indicator, or other external…
line driverAn amplifier used to enhance the transmission reliability of a usually digital intrafacility metallic transmission line, over extended distances, by…
line filter balanceA network designed to maintain phantom group balance when one side of the group is equipped with a carrier system.
line load controlA network-provided service feature that allows selective denial of call origination to certain lines when excessive demands for service are required of a…
line noiseIn a telecommunications link or line facility, interference, from any source, that degrades performance.
line sideThe portion of a device that is connected to external, i.e., outside plant, facilities such as trunks, local loops, and channels.
Line SourceAn array of pollutant sources along a defined path that can be treated in dispersion models as an aggregate uniform release of pollutants along a line.
line spectrumIn optics, an emission or absorption spectrum consisting of one or more narrow spectral lines, as opposed to a continuous spectrum.
line terminating equipment (LTE)Network elements that originate and/or terminate line signals. LTEs can originate, access, modify, or terminate the transport overhead, or can perform any…
line unit network termination (LUNT)The customer side of any digital subscriber line (DSL) that does not terminate on the customer installation (CI). [T1.216-1998]
line-of-sight (LOS) propagationOf an electromagnetic wave, propagation in which the direct ray from the transmitter to the receiver is unobstructed, i.e.
line-rate conversionA translation of standardized, existing video systems (using 525, 625, and 1125 total lines per frame) to proposed systems.