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