{HEAD ~ The incandescent filament lamps} are electrically connected in {TAIL ~ series} and powered by an AC power supply 
are electrically connected in
{ HEAD ~ The incandescent filament lamps } are electrically connected in { TAIL ~ series } and powered by an AC power supply
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH