MAX is a highly modular architecture. All capabilities are implemented by specific behaviors, or modules. At any one time only one behavior is active. Behaviors may invoke each other recursively because a stack of active behaviors is kept. Monitors are like behaviors but they are automatically invoked when some pre-defined environmental condition is met. They are used to respond to the dynamic environment in a timely manner, and they may be declared at runtime.
Go to a discussion of this property for multiple architectures.