FIG 3 is a timing diagram of {TAIL ~ an operation} of {HEAD ~ the controller} 140 
FIG 3 is a timing diagram of { TAIL ~ an operation } of { HEAD ~ the controller } 140
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH