DC1

from The Free On-line Dictionary of Computing (8 July 2008)

control-Q
DC1
XON

   <character> (Or XON, DC1, {Device Control} 1) The character
   with {ASCII} code 17, used in {software handshaking} to resume
   output after a previous {control-S}.

   [{Jargon File}]

   (1996-06-28)