Petri nets are an established and well researched means for systems modeling and simulation, but its use in the engineering community is not as widespread as the applicability of the formalism would suggest. A reason for this might lie in the fact that there is no established concept for the concise presentation of reusable Petri net design knowledge. This paper proposes Petri net design patterns as a style of presentation of such design knowledge ranging from building blocks to architectural considerations. The template for description is introduced using a number of examples taken from our design experience.