{HEAD ~ The light source} is capable of sending a light to the light receiving {TAIL ~ means} of the editing wheel 
{ HEAD ~ The light source } is capable of sending a light to the light receiving { TAIL ~ means } of the editing wheel
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH