Policy nets is an extension of Petri nets with step execution semantics, which is especially convenient for modelling GALS. 1)
1)
J.Fernandes, M.Koutny, M.Pietkiewicz-Koutny, D.Sokolov, A.Yakovlev: “Step persistence in the design of GALS systems”, Proc. International Conference on Application and Theory of Petri Nets(ATPN), pp.190–209, 2013.