R2

R2 / 1:M

Scenario plays out as a seqeuence of one or many System Interaction

System Interaction occurs in exactly one Scenario

---

We define a Scenario as a series of interactions with the target System. At the very least there might be a single stimulus (System Input) that initiates activity in the System. In any case, there must be at least one System Interaction for the Scenario to have any utility.