Model Parts, Diagrams, Dictionary Items, and Properties > Properties > Expression (property)
  
Expression (property)
For automation interface information about the Expression property (Change Expression through the automation interface), see the automation interface topic for an Event in the Related Topics.
This property specifies an expression that must be satisfied to trigger the Event.
By default, the Expression property is blank.
This property can be set on the Options tab of the Event's Property Pages. The Expression box is available only when the Event Type is set to Change Event.
The following section provides information about the items and diagrams for which Expression is a property. For more information about an item or diagram, click it.
Is property of
Event