NicatioNs> The traNsmissioN of extra data oN a chaNNel iN order to coNtrol the device seNdiNg data iN the other directioN oN that chaNNel. For aNEIA-232 coNNectioN, this meaNs seNdiNg CoNtrol-S aNd CoNtrol-Q characters to stop aNd start traNsmissioN. SiNce software haNdshakiNg requires the traNsmissioN aNd processiNg of extra data it caN be less efficieNt thaNhardware haNdshakiNg. (1996-10-16)