A virtual path link (VPL) or a virtual channel link (VCL). [T1.627-1993]

1. With reference to both analog and digital interfaces, the ATM functional unit and technology that operates with analog 2-wire interfaces and standard digital line rates on both the inputs and the outputs, e.g., DS1 on the input and DS3 on the output, and which passes the cells received on the input to the output. The relationship between input and… (Read More →)

A horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (a) are guided or focused within the duct, (b) tend to follow the curvature of the Earth, and (c) experience less attenuation in the ducts than they would if the ducts were not present.
Note: The reduced refractive index at the… (Read More →)

Radio noise caused by natural atmospheric processes, primarily lightning discharges in thunderstorms.

See International Atomic Time.

Acronym for acquisition and tracking orderwire. A downlink circuit that provides a terminal with information regarding uplink acquisition and synchronization status.

Advanced Television Systems Committee

In e-mail, a computer file that is transmitted with an e-mail message.
Note: Attachments are converted by an e-mail manager program, or by an add-on, to a MIME (multipurpose Internet mail extension) or binary format. The files are recovered by the recipient's e-mail manager program or by an add-on into their original, usually application-specific, format. [Bahorsky]

In a local area network, the interface between the medium access unit (MAU) and the data terminal equipment within a data station.

1. An attempt to violate computer security.
Note: An example of an attack is malicious logic. [2382-pt.8]
2. [An] intentional act of attempting to bypass one or more of the following security controls of an information system (IS): nonrepudiation, authentication, integrity, availability, or confidentiality. [INFOSEC-99]