{HEAD ~ A trigger coil} generates a trigger signal for application to {TAIL ~ the trigger} of the switches 
{ HEAD ~ A trigger coil } generates a trigger signal for application to { TAIL ~ the trigger } of the switches
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH