{HEAD ~ Users} are given {TAIL ~ specific subsets} of the database information to view at a given time, such as column definitions or the primary key definition 
are given
{ HEAD ~ Users } are given { TAIL ~ specific subsets } of the database information to view at a given time , such as column definitions or the primary key definition
HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH