The basic difference between the above definitions and the existing common definitions of information-related notions is: "Information system" and the related concepts belong to a methodology, not to an ontology. The correct question is whether a concrete system can be seen as an information system, not whether it is an information system. Whether a system can be seen as an information system not only depends on the features of the system, but also depends on the purpose of the observer who use the "information system" methodology. Therefore, when talking about information system, we always assume the existence of an observer with a specify purpose. It is not an "objective description".
Information system's behaviors are all goal-directed. A goal serves as an internal regulator of a system. Information system's nature is: its behavior is determined both by its goals and its environment. If a system's behavior can be completely explained by its current interaction with its environment, usually it is useless to describe the system as an information system.
The action of a system is the set of operations that the system can perform either on its internal structure or on its external environment. Usually there are basic operations whose internal structure cannot be further analyzed within the current information system framework, and compound operations that are time-space combination of simpler operations.
Beliefs are the internal connections of an information system. In the simplest form, a belief directly links a concrete goal to a concrete action that can be used to achieve the goal. In complicated situations, beliefs provide links among goals, actions, and other beliefs, therefore indirectly link goal to action.
The system's internal process cost time-space resources.
In an information system, both input and output processes can be seen as actions of the system taken to achieve some goals. An input action can either be triggered by an internal goal, or by an external signal, or "stimulus". The consequence of the action is knowledge of the system, corresponding to the state or state change in the environment. An output action can also be triggered internally or externally. The consequence of the action is certain state changes inside (in the system) or outside (in the environment), as a spontaneous motion or response to a stimulus, respectively.
When an input action and an output action are considered together, we see a "stimulus-response" cycle or an "motion-feedback" cycle. The streams of input actions and output actions in a period of time form the system's experience and behavior, respectively.