storing the protection level of each of the set of {HEAD ~ data} stored in {TAIL ~ the leaf nodes}; and 
stored in
storing the protection level of each of the set of { HEAD ~ data } stored in { TAIL ~ the leaf nodes } ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH