Architecting and designing : IDEF : IDEF3 : Modeling processes with IDEF3 : Defining a Scenario in IDEF3 Process Modeling
  
Defining a Scenario in IDEF3 Process Modeling
There are two ways to define a scenario.
▪edit a scenario symbol in a top-level IDEF3 process diagram
▪edit the diagram properties and add a scenario
See also
Modeling processes with IDEF3