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