In computer science, the highest level of a hierarchy.

The Root Cause is the primary problem which once identified and corrected will prevent the same or a similar reportable incident from recurring (i.e., why the reportable incident happened). A Root Cause should be actionable.

A single quantity, rms, characterizing a function, f(x), given by
Note: The term "rms deviation" is also used in probability and statistics, where the normalization, M0, is unity. Here, the term is used in a more general sense.

The temporal rms deviation of the impulse response of a system.

A special case of root-mean-square deviation where the independent variable is time and f(t) describes the pulse waveform.

A conductor composed of a central core surrounded by one or more layers of helically wound groups of wires.

A signaling mechanism--usually incorporated within a telephone set--that when rotated and released, generates dc pulses required for establishing a connection in a telephone system.

Hunting in which all the numbers in the hunt group are selected in a prescribed order.
Note: In modern electronic switching systems, the numbers in the hunt group are not necessarily selected in consecutive order.

In telephone systems, an electro-mechanical switching method whereby the selecting mechanism consists of a rotating element using several groups of wipers, brushes, and contacts.

[In magnetic media,] A technique used to locate a given sector, a desired track, and a specific record by continuous comparison of the read/write head position with appropriate synchronization signals.