You can assign a Signal only to Send or Call (synchronous or asynchronous) Messages. Only one Signal can be assigned to a Message.

If a Signal is assigned to a Call Message, the Message is automatically converted to a Send Message.



To assign a Signal to a Message by dragging


  1. Select a Signal in the Containment tree.
  2. Drag the selected Signal to a desired Message.


To assign a Signal to a Message by typing Message name

  • Click the Message to type the Message name on the diagram. A Signal is automatically created with the same name as Message name.


To assign a Signal to a Message from the Message Specification window


  1. Draw a Send Message between two Lifelines or select an existing one on a diagram pane.
  2. Open the Message Specification window.
  3. Click the Signature (signal) property value cell and then select a Signal in the drop-down list.

Names of signal attributes are displayed in the message signature by default. However, you can change this behavior by opening the Symbol Properties dialog (right-click a Message and select Symbol Properties) and setting the Show Attribute/Parameter Names property to true to display them or false to hide them.

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