In philosophy, a process ontology refers to a universal model of the structure of the world as an ordered wholeness. Such ontologies are fundamental ontologies, in contrast to the so-called applied ontologies. Fundamental ontologies do not claim to be accessible to any empirical proof in itself but to be a structural design pattern, out of which empirical phenomena can be explained and put together consistently. Throughout Western history, the dominating fundamental ontology is the so-called substance theory. However, fundamental process ontologies are becoming more important in recent times, because the progress in the discovery of the foundations of physics spurred the development of a basic concept able to integrate such boundary notions as "energy," "object", and those of the physical dimensions of space and time. In computer science, a process ontology is a description of the components and their relationships that make up a process. A formal process ontology is an ontology in the knowledge domain of operations. Often such ontologies take advantage of the benefits of an upper ontology. Planning software can be used to perform plan generation based on the formal description of the process and its constraints. Numerous efforts have been made to define a process/planning ontology. Processes A process may be defined as a set of transformations of input elements into output elements with specific properties, with the transformations characterized by parameters and constraints, such as in manufacturing or biology. A process may also be defined as the workflows and sequence of events inherent in processes such as manufacturing, engineering and business processes. Ontologies PSL The Process Specification Language (PSL) is a process ontology developed for the formal description and modeling of basic manufacturing, engineering and business processes. This ontology provides a vocabulary of classes and relations for concepts at the ground level of event-instances, object-instances, and timepoints. PSL’s top level is built around the following: Activity – a class or type of action, such as install-part, which is the class of actions in which parts are installed Activity-occurrence – an event or action that takes place at a specific place and time, such as a specific instance of install-part occurring at a specific timestamp Timepoint – a point in time Object – anything that is not a timepoint or an activity Cyc In a process/planning ontology developed for the ontology Cyc, classes and relations above the ground level of PSL allow processes to be described