FIG 1 illustrates {HEAD ~ the basic principle} of {TAIL ~ the trace} according to the invention 
of
FIG 1 illustrates { HEAD ~ the basic principle } of { TAIL ~ the trace } according to the invention
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH