A frame support structure having four frame engaging members is automatically displaced to {HEAD ~ a frame} receiving {TAIL ~ position} 
receiving
A frame support structure having four frame engaging members is automatically displaced to { HEAD ~ a frame } receiving { TAIL ~ position }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL