Actions can be further defined with pre-condition and post-condition notes, which constrain an Action's entry and exit. These notes can be added to an Action as defined below.

See UML Superstructure Specification, v2.0, figure 200, p. 283.
Create a Constraint
To attach a constraint to an Action follow the steps below:
1. | Right-click on the action. The context menu displays: |
2. | Select the menu option. A Note is created on the diagram, linked to the action. |
3. | Right-click on the Note. The context menu displays. |
4. | Select the menu option. The Constraint dialog displays.

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5. | In the field, click on the drop-down arrow and select the required constraint type. |
6. | In the field, type the text for the constraint. |
7. | Click on the button to save the constraint. |