The scope of this part of ISO 18629 is the provision of an overview of the whole ISO 18629 and of the main underlying principles of the Process Specification Language. This part of ISO 18629 also specifies the characteristics of the various series of parts in ISO 18629 and the relationships among them. The following are within the scope of this part of ISO 18629: — general overview of ISO 18629 and of the main principles used; — structure of ISO 18629 and relationships between the series of parts of which this standard is composed; — definitions of terms used throughout ISO 18629; — conformance criteria for process-related applications; — conformance criteria for other ontologies; — conformance criteria for parts of ISO 18629. The scope of this part of ISO 18629 includes providing explanations addressing the following items: — Annex B: Background to the development of ISO 18629; — Annex C: Need for semantics; — Annex D: Interoperability; — Annex E: Architecture of PSL.