The shuttle element may serve as an indicator or signaling element, either alone or together with the above described functions, so as to signal to a sensor that the transition or {HEAD ~ boundary} between the paint and {TAIL ~ the auxiliary medium} has reached a certain sensing location 
between
The shuttle element may serve as an indicator or signaling element , either alone or together with the above described functions , so as to signal to a sensor that the transition or { HEAD ~ boundary } between the paint and { TAIL ~ the auxiliary medium } has reached a certain sensing location
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH