The bus also enables {TAIL ~ the execution} of I/O operations that originated in external controllers and transmitted over {HEAD ~ the communication network} 
The bus also enables { TAIL ~ the execution } of I / O operations that originated in external controllers and transmitted over { HEAD ~ the communication network }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD