{HEAD ~ The outputs} of the individual power sources are responsive and proportional to {TAIL ~ individual input control signals} 
are proportional to
{ HEAD ~ The outputs } of the individual power sources are responsive and proportional to { TAIL ~ individual input control signals }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL