{HEAD ~ The buses} of {TAIL ~ one layer} are connected to the appropriate bus of the other layer using through holes located in the array 
of
{ HEAD ~ The buses } of { TAIL ~ one layer } are connected to the appropriate bus of the other layer using through holes located in the array
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH