{HEAD ~ The runner} is accommodated at the fixing portion, and is capable of up and down sliding movements at {TAIL ~ the fixing portion} 
{ HEAD ~ The runner } is accommodated at the fixing portion , and is capable of up and down sliding movements at { TAIL ~ the fixing portion }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL