Introduction

Object-Process Methodology (OPM) is a compact conceptual approach, language, and methodology for modelling and knowledge representation of automation systems. The application of OPM ranges from simple assemblies of elemental components to complex, multidisciplinary, dynamic systems. OPM is suitable for implementation and support by tools using information and computer technology. This document specifies both the language and methodology aspects of OPM in order to establish a common basis for system architects, designers, and OPM-compliant tool developers to model all kinds of systems.

OPM provides two semantically equivalent modalities of representation for the same model: graphical and textual. A set of hierarchically structured, interrelated Object-Process-Diagrams (OPDs) constitutes the graphical model, and a set of automatically generated sentences in a subset of the English language constitutes the textual model expressed in the Object-Process Language (OPL). In a graphical-visual model, each OPD consists of OPM elements, depicted as graphical symbols, sometimes with label annotation. The OPD syntax specifies the consistent and correct ways to manage the arrangement of those graphical elements. Using OPL, OPM generates the corresponding textual model for each OPD in a manner that retains the constraints of the graphical model. Since OPL's syntax and semantics are a subset of English natural language, domain experts easily understand the textual model.

OPM notation supports the conceptual modelling of systems with formal syntax and semantics. This formality serves as the basis for model-based systems engineering in general, including systems architecting, engineering, development, life cycle support, communication, and evolution. Furthermore, the domain-independent nature of OPM opens system modelling to the entire scientific, commercial and industrial community for developing, investigating and analysing manufacturing and other industrial and business systems inside their specific application domains, thereby enabling companies to merge and provide for interoperability of different skills and competencies into a common intuitive yet formal framework.

OPM facilitates a common view of the system under construction, test, integration, and daily maintenance, providing for working in a multidisciplinary environment. Moreover, using OPM, companies can improve their overall, big-picture view of the system's functionality, flexibility in assignment of personnel to tasks, and managing exceptions and error recovery. System specification is extensible for any necessary detail, encompassing the functional, structural and behavioural aspects of a system.

One particular application of OPM is in the drafting and authoring of technical standards. OPM helps sketch the implementation of a standard and identify weaknesses in the standard to reduce, thereby significantly improving the quality of successive drafts. With OPM, even as the model-based text of a system expands to include more details, the underlying model keeps maintaining its high degree of formality and consistency.

This document provides a baseline for system architects and designers, who can use it to model systems concisely and effectively. OPM tool vendors can utilise this document as a formal standard specification for creating software tools to enhance conceptual modelling.

This document provides a presentation of the normative text that follows the Extended Bachus Naur Form (EBNF) specification of the language syntax. All elements are presented in Clause 6 to 13 with only minimal reference to methodological aspects, Clause 14 presents the context management mechanisms related to in-zooming and unfolding.

NOTE OPM is an established modelling paradigm with a 15-year history of use in international commerce. As such, several conventions for its use and presentation already exist in the literature and practice.

This document uses the presentation conventions for the expression of OPM related constructs found in the originating and current literature for OPM. Using a different set of conventions, or simply applying the ISO/IEC Directives, Part 2 drafting guidelines for these terms and presentations, creates a discontinuity between this document and the supporting references and practice, and can cause confusion in application of this document to existing and future practice.

This document applies the following conventions for the presentation of OPM elements and terminology:

— The phrases and associated abbreviations “Object-Process Methodology (OPM)”, “Object-Process Diagram (OPD)” and “Object-Process Language (OPL)” are terms of art associated with the OPM paradigm and appear as specified with the hyphen and capitalization of each word in the phrase.
— In OPD and OPL text, the object name and process name appear in Cambria bold font text with capitalization of each word to distinguish the object and process from the other OPD and OPL text. The same convention for object and process name bold capitalization is carried into the text of this document as well to indicate that in the text, the word or phrase corresponds to an OPM object or process.
— In OPD and OPL text, the object state label and attribute value label appear in Cambria bold font text in lowercase, and somewhat smaller font in OPD figures, to distinguish the object state label and attribute value label from the other OPD and OPL text. The same convention for object state label and attribute value label in bold font lowercase is carried into the text of this document as well to indicate that in the text, the word or phrase corresponds to an OPM object state label or attribute value label.
— In OPD and OPL text, link tags that are not user-specified appear in Cambria lowercase, and somewhat smaller font in OPD. Link tags that are user-specified appear as entered by the user in Cambria bold font text, and somewhat smaller font in OPD.
— In OPL, the first letter of the first word of a sentence is capitalized.
— Some of these conventions are repeated in the text as appropriate to remind the reader of the distinctions. Some OPD figures contain colour to help distinguish OPM modelling element type distinctions.

Most figures contain both a graphical image, the OPD portion, and a textual equivalent, the OPL portion of the figure. Because this is a language specification, the precise use of term definitions is essential and several terms in common use have particular meaning when using OPM. In addition to those listed above as OPM presentation conventions, Annex B explains other conventions for the use of OPM.

Annex A presents the formal syntax for OPL, in EBNF form.

Annex B presents conventions and patterns commonly used in OPM applications.

Annex C presents aspects of OPM as OPM models.

Annex D summarizes the dynamic and simulation capabilities of OPM.

BS ISO 19450:2024

Automation systems and integration. Object-Process Methodology

Current

Published:

31 Jan 2024