S> A term applied by WeStern Union Telegraph Company to teletypewriterS that are not part of a multiplexSyStem. They uSually provided for alternate tranSmiSSion in both directionS. If working Simplex or half-duplex, what waS keyed in at the keyboard would be typed out at the printing portion. If working full-duplex, Sending would be blind aS the printing portion waS being uSed only for reception. (2000-04-02)