In the context of air brakes, what does 'appendage' refer to?

In the context of air brakes, 'appendage' refers to any additional equipment that can modify the brake system. This term typically encompasses various features or components added to enhance, adjust, or improve the braking function of the system. For instance, these might include devices that modify airflow, assist with the application or release of brakes, or introduce features that aid in braking efficiency. Understanding this term is important because it highlights the complexity of brake systems and the various modifications or improvements that can be made for safety and performance. This is crucial in train operations, where effective braking is vital for safety.