There is apparatus for creating a beam of a material being input thereto and for selectively including or not including {TAIL ~ respective ones} of a plurality of materials within {HEAD ~ the beam} 
There is apparatus for creating a beam of a material being input thereto and for selectively including or not including { TAIL ~ respective ones } of a plurality of materials within { HEAD ~ the beam }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD