This abstraction is used to construct the process ontology. The process ontology includes systems theory and specializes the system theoretic concepts to processes. Just like the component ontology, the process ontology defines relatively simple concepts and relations onto which the system ontology is projected. This can be seen in Figure 7 . Mechanisms are defined as simple mereological individuals.
Energy flows, which have a certain direction, flow from one mechanism to another.
The projection is performed by stating that an energy flow is a topological connection that connects the two mechanisms. A process description can now simply be defined as a system of mechanisms. The taxonomy of physical mechanisms. The properties discriminating between the classes after branching are printed above the branch points. The classes on the right give some examples of mechanisms in the electrical and mechanical domain.