If your spec includes timing constraints (which all hardware specifications do!)

We want to control two lights of G and W with a set of timing constraints.

Timing diagrams: a specific type of interaction diagram where the focus is on timing constraints.

Real-time software systems have strict timing constraints and have a deterministic behavior.

This is so because real time software systems have to schedule their tasks such that the timing constraints imposed on them are met.

Conventional static way of analysis is not adequate to deal with such timing constraints, hence real time testing is important.

Order of the events doesn't matter as task testing doesn't deal with timing constraints and time properties of events.

Wiring a control panel required knowledge of the machine's components and their timing constraints.

All the tasks and their timing constraints are known at compile time in a system where priorities are static.

Using this method, it is theoretically possible to create fully resolved phylogenetic trees, and timing constraints can be recovered more accurately.