Each of the partitions has hooks and {HEAD ~ notches} to help hold {TAIL ~ the assembly} together 
to help hold
Each of the partitions has hooks and { HEAD ~ notches } to help hold { TAIL ~ the assembly } together
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH