An instrument provides evidence which may be presented in subsequent conversations. The receipt, for example, is a record which shows that the holder purchased the goods and who supplied them. Where the significance of the exchange is very high, then concepts like third party notarisation are used to ensure the dependability of an instrument. Systems objects The second encapsulation of the basic abstractions produces another type of object which is required to model enterprise. In this case we group together activity and resource to make systems objects.
Controller objects support sensing and manipulation of plant and material.
Manager objects support configuration and monitoring of plant and material. Fig 3 shows the case of the encapsulation of information and computational resource to construct computational objects . Here the interaction takes the form of invocation. So, in Fig.3 we are representing a very simple case where the invocations between two information systems objects represent an implementation of a role relationship. The automation of activity does not remove the responsibilities associated with it but redistributes them between a systems design epoch and an operational epoch onto roles such as architect, designer, maintainer, operator and user.