Synonym illegal character.

With respect to telecommunications plant, any current that is not intentionally supplied from the central office or from telephone equipment. [After T1.316-1997]

With respect to telecommunications plant, any voltage that is not intentionally supplied from the central office or from telephone equipment. [After T1.316-1997]

Unified Ordering Model

A device that translates frequencies from lower to higher frequencies.

Universal Powerline Bus

The regeneration of a display to show current status, based on changes to the previously displayed data.
Note: An update can be accomplished upon user request or by automatic means.

[In INFOSEC, an] automatic or manual cryptographic process that irreversibly modifies the state of a COMSEC key, equipment, device, or system. [INFOSEC-99]

To change a MAC label or Information Label to a label that dominates the current label but is not equivalent to the current label [POSIX.6].

1. The portion of a communications link used for the transmission of signals from an Earth terminal to a satellite or to an airborne platform.
Note: An uplink is the converse of a downlink.
2. Pertaining to data transmission from a data station to the headend.