{HEAD ~ a first rotatable means} for controlling {TAIL ~ the horizontal movement} of said cover through Said linear means, 
for controlling
{ HEAD ~ a first rotatable means } for controlling { TAIL ~ the horizontal movement } of said cover through Said linear means ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH