The course of developmental changes through which a system passes from its conception to the termination of its use and subsequent salvage.
Note: For example, a system life cycle might include the phases and activities associated with the analysis, acquisition, design, development, test, integration, operation, maintenance, and modification of the system.

In a frequency-division multiplexed (FDM) transmission system, the absolute power level of the composite signal transmitted in one direction.
Note 1: The absolute power level is referred to a zero transmission level point (0TLP).
Note 2: The composite signal contains signaling, speech, and digital signals.

1. Network management functions extended to include subscriber elements or user end instruments.
2. In computer systems, synonym system administration.

The person ultimately responsible for the production and enforcement of a System Security Policy [CESG]. See also: System Administrator, System Security Officer.

For a supported performance parameter of a system, the value that establishes the minimum operational service performance level for the parameter.
Note: A measured parameter value worse than the system operational threshold indicates that the system is in an outage state.

See overhead information.

Synonym power margin.

[In INFOSEC, the] detailed security description of the physical structure, equipment component, location, relationships, and general operating environment of an information system (IS). [INFOSEC-99]

The probability that a system, including all hardware, firmware, and software, will satisfactorily perform the task for which it was designed or intended, for a specified time and in a specified environment. [From Weik '89]

The measure or extent of the ability of a system, such as a computer, communications, data processing, or weapons system, to continue to function despite the existence of faults in its component subsystems or parts.
Note: System performance may be diminished or otherwise altered until the faults are corrected.