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