||Interface used for implementing an event handler that is invoked
||Encapsulates information about an event captured by a callback object.
||Interface used by implementations of the "CLASSNAME" given in
"SYS.ADD_LISTENER" and "SYS.ATTACH_WRITER" procedures.
||This interface should be implemented by the user to insert an entire row.
||Used to represent the meta-data information of a table, or projection of some
columns of a table.