a control unit that carries out connection and disconnection to and from each of {HEAD ~ the host computers} as {TAIL ~ sources} of print requests according to the host information registered in said registration unit 
as
a control unit that carries out connection and disconnection to and from each of { HEAD ~ the host computers } as { TAIL ~ sources } of print requests according to the host information registered in said registration unit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH