Car Example
The car module diagram shown to the left illustrates several sub-modules that form a hierarchical structure. This configuration allows feature swapping, like a new engine, without impacting the overall system.
More importantly, by creating a hierarchical structure, we have increased safety because each instrument no longer has direct access to each other. For example, the cruise control system must navigate the engine and ignition control modules before igniting a sparkplug. The ignition control might have more information, like from the traction control system, to refuse the request.