AbstractPetri nets are a subject of interest to researchers since more than 30 years. They became popular since they allow the graphic representation of computational structures and have a formal underpinning that allows formal proofs of properties. Their use in engineering, however is limited to a rather small number of applications. Many of the graphic notations used in practice are very similar to the graphic representation of Petri nets but do not make use of the rich body of theory that exists for Petri nets. This is repeatedly attributed to the fact that Petri nets and the associated theory are hard to understand and real life problems modelled with Petri nets tend to require special brands of Petri nets which in turn led to a great v...