Markov regenerative stochastic Petri nets with general execution policies: Supplementary variable analysis and a prototype tool. Stochastic Petri Nets (SPNs) with general firing time distributions are considered. Generally timed transitions can have general execution policies: the preemption policy may be preemptive repeat different or preemptive resume and the firing time distribution can be marking-dependent. A stationary analysis method covering all possible combinations is presented by means of supplementary variables. The method is implemented in a prototype tool SPNica which is based on Mathematica. The use of the general execution policies is illustrated by a WWW server model.