The couplings are mounted in the floor of {HEAD ~ the structure} and are constructed and secured in the floor such as to prevent fire and smoke from passing around the couplings between the couplings and {TAIL ~ the floor} 
The couplings are mounted in the floor of { HEAD ~ the structure } and are constructed and secured in the floor such as to prevent fire and smoke from passing around the couplings between the couplings and { TAIL ~ the floor }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL