Around {HEAD ~ the notch} 43 is {TAIL ~ a plurality} of pivotally disposed main ribs 45 for supporting the cover 41 
is
Around { HEAD ~ the notch } 43 is { TAIL ~ a plurality } of pivotally disposed main ribs 45 for supporting the cover 41
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH