{HEAD ~ Controller} 140 includes a matrix of {TAIL ~ apertures}, 144, the apertures of which correspond in size and number to those of matrix 138 
{ HEAD ~ Controller } 140 includes a matrix of { TAIL ~ apertures } , 144 , the apertures of which correspond in size and number to those of matrix 138
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH