1. Structuring descriptions by description level

One of the main advantages of the revised IEC 60848 standard is that it provides a means of structuring the specification. This structuring, which may or may not be supported by appropriate methodologies, can be limited to a partition of the grafcet, or use macro-steps, integrate notions of hierarchy by forcing, or use encapsulation.

Some of these concepts (macro-stage and forcing), which appeared in various publications, were used by the community, but were not standardized.

Macro-step, grafcet partition and encapsulating step representations have the following advantages:

• obtain homogeneous representations of behavior that...