In UML modeling, a guard condition is a boolean condition
that is evaluated when a transition initiates. A transition with a
guard condition occurs when the guard condition is evaluated to
be true.
Before you can add a trigger to a transition,
you must have a state machine diagram open in the Modeling perspective.
To add a guard condition to a transition:
- Right-click a transition; then click .
- In the parentheses beside the transition name, describe
the guard condition and press Enter.