The scope of this standard is: ? Covers real-time batch@ discrete and continuous process automation systems. ? Defines regulatory@ event-driven and time-driven control system actions. ? Encompasses both digital and analog control devices in addition to non-control actions (for example@ operator messages and batch end reports). ? Encompasses both normal and abnormal operational requirements of systems and shows the interactions between them. ? Uses a set of terms that relate directly to the languages commonly used by plant operators. ? Excludes interactions with higher-level systems. Within the parameters of this scope@ the standard is intended to: ? Establish functional requirements specifications for control software documentation that covers the classes of industrial automation equipment and systems consisting of distributed control systems@ programmable controllers and industrial personal computers (see Figure 1). ? Provide techniques for documenting control system software. The software to be generated is a function of the computer system chosen for a particular project. The documentation procedure set forth in this standard is independent of the hardware/software system that is chosen. ? Provide a basis for validation of run-time application software after it is developed and tested to ensure that the initial requirement specification has been met. The documentation resulting from use of this standard: ? Can be used for control software definition@ design@ testing and validation. ? Is not intended to require specialized knowledge of any particular engineering or computer science discipline to develop or understand.