When {HEAD ~ the lid} is in the first position it covers {TAIL ~ substantially all} of the top opening of the container 
When { HEAD ~ the lid } is in the first position it covers { TAIL ~ substantially all } of the top opening of the container
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH