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