In sequence diagrams, a guard condition, or an interaction constraint,
is a semantic condition or restriction in an interaction operand within a
combined fragment. A guard condition is created automatically when you create
a combined fragment. You can also manually add a guard condition in an interaction
operand that does not have an existing guard condition.
You must have a sequence diagram that contains at least one combined
fragment with multiple lifelines open.
To add a guard condition to an interaction operand:
- In the diagram editor, right-click an interaction operand that
has no existing guard condition; then click .
- Click the field, type the guard condition, and press Enter.
Note: In a loop combined fragment, you can edit the guard
condition using the textual syntax [ ‘(‘ <minint> [, <maxint>
] ’)’ ], where minit and maxint are
non-negative integers, and state the minimum and maximum number of times that
a loop can occur.