At least two frame engaging {HEAD ~ members} of the frame support structure are moved to position the side members of {TAIL ~ the frame} in a desired configuration 
At least two frame engaging { HEAD ~ members } of the frame support structure are moved to position the side members of { TAIL ~ the frame } in a desired configuration
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH