This volume documents the progress of application and theory of Petri Nets since the Advanced Course on General Net Theory of Processes and Systems, held in Hamburg, October 8-19, 1979, This course presen ted in detail wha t had been achieved in this area since the first studies of concurrent systems 20 years ago, After this course it seemed worthwhile to establish a co-operation between different groups working in the field of Petri N ets, The starting points were the AFCET Special Interest Group Systemes Paralleles et Distribues and the Gl Special Interest Group Petrinetze und verwandte...