{TAIL ~ A plurality} of mass gas flow controllers are arranged to control flow into {HEAD ~ a respective inlet port} 
{ TAIL ~ A plurality } of mass gas flow controllers are arranged to control flow into { HEAD ~ a respective inlet port }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD