{HEAD ~ The system} allows {TAIL ~ a user} to create a semantic object data model of the database schema 
allows
{ HEAD ~ The system } allows { TAIL ~ a user } to create a semantic object data model of the database schema
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH