Operating Diagrams (OD) are a particularly elegant way of graphically representing the asymptotic behavior(s) of a dynamic system. Provided that the model of the system of interest is well known, they enable the asymptotic behavior of the system to be determined as a function of the process input parameters. As we shall see, they can also be used to discover new system properties, or at the very least, devise new control strategies that would not otherwise have been discovered. In this way, we have discovered that it is sometimes possible to stabilize a multi-stage bioprocess by increasing the dilution ratio, rather than lowering it, as it is classically the case.