at least a portion of {TAIL ~ said first recess} a being aligned with said {HEAD ~ second opening} 
at least a portion of { TAIL ~ said first recess } a being aligned with said { HEAD ~ second opening }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD