This chapter discussed unfinished concepts in 88.01. The definitions in Section 3 of the standard could be made normative with some work, after being proven by ten years of use. The Physical Model needs at least two more layers and needs clearer explanation of some layers, particularly the abstract modules that are not really physical.

88 Batch Control Concepts needs a section on "Equipment entities and the Purdue Reference Model" to prevent some misunderstandings with SP95. The section on Exception Handling could be made substantive with a discussion of the various ways that are available to handle exceptions. Such a discussion was included in this chapter. Modes and states were discussed. That discussion could clarify 88.01.

The recipe procedural element called an operation was discussed, with some reasons why operations should not be run in parallel. An alternative to the use of unit procedures was described. The agitator phase problem was discussed as a possible reason for unnecessary parallel operations. The ownership of a common valve between two units was covered and a solution proposed.

Batch Control Activities could benefit from more discussion of the translation problem, especially in regard to translating non-88 recipes into the standard formats. A discussion of the execution of procedural elements is in this chapter, which might be an aid to understanding procedural control in 88.01. 88.01 has no discussion of recipe calculations, so that subject was also covered in this chapter.

Procedure function charts were discussed because they have not caught on as...