Model Parts, Diagrams, Dictionary Items, and Properties > Properties > Sequence number (property)
  
Sequence number (property)
This property specifies the sequence number for an instance of an Event or Operation:
An Event Instance on a Concurrency Diagram, Communication Diagram or System Architecture Diagram.
An Operation Instance on a Concurrency Diagram or Communication Diagram
The Sequence Number indicates the relative execution order of the messages on the diagram.
By default:
For the first Event or Operation instance added to a diagram, the Sequence Number is set to 1.
For the second Event or Operation instance added to a diagram, the Sequence Number is set to 2, and so on.
You can delete or change the default Sequence Number.
On a diagram, the Sequence Number appears above the Event or Operation name.
This property is set on the Options tab of the Property Pages for an Event Instance (message) or Operation Instance (message). To view an instance's Property Pages, on the diagram, right-click the item, and then click Instance Properties.
The following section provides information about the items and diagrams for which Sequence Number is a property. For more information about an item or diagram, click it.
Is property of
Event Instance (message)
Operation Instance (message)