Concepts: http://docs.oracle.com/cd/E16655_01/server.121/e17633/cdbovrvw.htm#CEGIJFBI

Administrator's Guide: http://docs.oracle.com/cd/E16655_01/server.121/e17636/cdb_plug.htm#CEGEFFCG

SQL language reference: http://docs.oracle.com/cd/E16655_01/server.121/e17209/statements_6009.htm#CCHDHBCJ