ehaviour defined by the set of predefined opera- tions that are shown in Fig. 7.54. All objects are interpreters of AML specifica- tions. The machine acts as a specified service object when the specifications (operation specifications, resource model, behaviour specification) that describe that object are compiled into the machine. In early development phases, one can expect the operation specifications to be in the symbolic form with behaviour being described as one or several state diagrams, i.e. not machine interpretable. When the state machine model will be used, these specifications must first be refined into machine-interpretable specifications. This means typing operation specifications, translating the resource model into a data model (a state vector) and translating the state diagrams into a set of event specifications. 7 Concepts and Notations for Process Control Systems Modelling The virtual object FSM: devC_REP gevORD ProviderPort Object Event object existsREQ Service postORD Activity queryREQ State preREQ objects postORD Object intEventC_REP The agent FSM: ProviderPort Object Event object UserPort UserPort devC_REP Object Object Object gevORD State Object Activity Activity object object The actor FSM: Event object Object UserPort UserPort State Object Object Object Activity Activity object object Fig. 7.54 The AML general state machine model applied to virtual objects, agents and actors This process (whether a manual or a tool-supported process) is depicted in Fig. 7.55. The figure also shows what object handles each compiled specification. There are many ways a resource model can be translated to a data model (i.e., to a state vector). For simple models, such as the one that was used in the dressing case in Sect. 7.5.2, a simple ASN.1 type assignment for State can be produced, see Figs. 7.43 and 7.46. For more complicated models that define relations and several entity types, a more elaborated technique based on set and functions is recom- mended. Producing a typed operation specification out of a s