a plurality of {HEAD ~ gas outlet ports} selectively in fluid communication with the plurality of gas inlet ports and {TAIL ~ first and second gas inlets} of the processing chamber 
a plurality of { HEAD ~ gas outlet ports } selectively in fluid communication with the plurality of gas inlet ports and { TAIL ~ first and second gas inlets } of the processing chamber
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH