A cover may be placed over the upper opening to seal {HEAD ~ the main body} against {TAIL ~ contamination}, permitting storage of the material 
against
A cover may be placed over the upper opening to seal { HEAD ~ the main body } against { TAIL ~ contamination } , permitting storage of the material
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH