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