Message Sequence Chart (MSC) is commonly used to represent the dynamic behaviour between two processes or applications. These inter communications can be found in most of the applications and systems. TestOptimal uses MSC to visualize these dynamic behaviours. Below is an MSC that describes the transition traversals of a model execution:

In the above MSC, each message represents a transition traversal a source state to a target state.

Complex test scenarios may involve multiple models to synchronize and communicate together. The following are examples of inter-model operations:

1. setting user variables remotely in another model execution
2. sending signal to activate a state in another model execution
3. sending signal to trigger a transition in another model execution