Starting point Digital Factories assume a single machine that represents a hand router. If a Digital Factory Administrator adds machines, aPriori selects only from preferred machines, if there is a preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point Digital Factories). If there is no preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.