{HEAD ~ The stopper mechanism} controls and releases retraction of the retractable unit to the closed position in which the unit is retracted, and includes {TAIL ~ a stopper} and a blocking member 
includes
{ HEAD ~ The stopper mechanism } controls and releases retraction of the retractable unit to the closed position in which the unit is retracted , and includes { TAIL ~ a stopper } and a blocking member
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH