566759e4_DBMS_SCHEDULER__Description
[Parameter] event_condition [Description] 
This is a conditional expression based on the columns of the event source queue table. The expression must have the syntax of an Advanced Queuing rule. Accordingly, you can include user data properties in the expression provided that the message payload is an object type, and that you prefix object attributes in the expression with tab.user_data. For more information on rules, see the DBMS_AQADM.ADD_SUBSCRIBER procedure.
DBMS_SCHEDULER
Description