A multi phase generator has {HEAD ~ a separately excited shunt field} which is controlled by {TAIL ~ a voltage regulator} 
is controlled by
A multi phase generator has { HEAD ~ a separately excited shunt field } which is controlled by { TAIL ~ a voltage regulator }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL