A mathematical model has been developed to determine the timing of the tasks that can be performed on a variety of units to produce a variety of end states and to monitor the flow of the material through the network. The mathematical model is based on the work of Kondili et al. (1993) and is extended with the ability to monitor and restrict the shelf-life of a state, the ability to implement a mandatory storage action with shared storage and the ability to implement batch-size dependent processing times for batch-sizes that can only take a certain value.