Another advantage is that tracking records do not have to be explicitly created in a tracking operation for {HEAD ~ marked items} contained in {TAIL ~ another marked item} 
contained in
Another advantage is that tracking records do not have to be explicitly created in a tracking operation for { HEAD ~ marked items } contained in { TAIL ~ another marked item }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL