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