An interaction operand is a container that groups interaction fragments in a combined fragment. An interaction operand contains an optional guard condition, which is also called an interaction constraint. The interaction operand runs only if the guard condition tests true.
How to model an InteractionOperand
1 Use the InteractionOperand symbol on the Draw toolbar of the Sequence diagram for SysML or UML 2.5, and draw it on a Sequence diagram within a Combined Fragment (see image below). The InteractionOperand creates a split of the Combined Fragment.
2 Use the InteractionConstraint symbol to add Guard conditions for each Combined Fragment. In the example below, Guard conditions include [unacceptable], [proposal1 best], and [proposal2 best] – all drawn as InteractionOperands.
