This is a Special Interest Group (SIG) for anyone interested in Object-Process Methodology (OPM) which 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 has been adopted by the International Organization for Standardization, ISO, and on December 7, 2015 it was published as a normative ISO 19450 document at https://www.iso.org/obp/ui/#iso:std:iso:pas:19450:ed-1:v1:en. Over the past two decades, Prof. Dov Dori of the Faculty of Industrial Engineering and Management at the Technion has been developing Object-Process Methodology (OPM) as a language and method for conceptual modeling of complex systems of any kind, be it artificial or natural. An OPM model expresses both graphically and textually the architecture of the system: Interconnected diagrams at varying levels of detail, from a bird's eye view to any desired number of "nuts and bolts" views, specify any conceptual and logical aspect of the system. Each graphic expression is translated on the fly to a corresponding textual specification in a plain subset of English. A basic premise underlying OPM is that one can build a model of any system in any domain and at any level of complexity with the most minimal set of building blocks: stateful objects (objects with states) and processes that create or consume objects, or change their states. Over the last decade, Technion students at the Enterprise Systems Modeling Laboratory developed OPCAT (Object-Process CASE Tool), a software package that is available freely from the Lab's website http://esml.iem.technion.ac.il/ and translates the user's graphic input into simple English in real time. This enables quick model development jointly by the customer and the system architects and engineers, and reliable verification of the model as it is being created. The SIG is managed by Dr Pathmeswaran Raju of Cranfield University, UK.