A node whose behavior can be controlled by the user should be derived from BControllable, as well as from whatever other interface classes the node might be derived from. Deriving from BControllable lets the node publish information about the parameters that can be adjusted and how they relate to each other.

A client application can use the published information to build a user interface for the node or pass the information through to a system routine that will build the interface.

A node can also have the ability to start its own control panel under outside control, which can take advantage of special knowledge of the node.