This Publicly Available Specification specifies Object-Process Methodology (OPM) with detail sufficient for enabling practitioners to utilise the concepts, semantics, and syntax of Object-Process Methodology as a modelling paradigm and language for producing conceptual models at various extents of detail, and for enabling tool vendors to provide application modelling products to aid those practitioners.While this Publicly Available Specification presents some examples for the use of Object-Process Methodology to improve clarity, it does not attempt to provide a complete reference for all the possible applications of Object-Process Methodology.