Process taxonomy modules are evaluated for each feasible process in the context of a particular stock selection, process routing, and machine selection. A routing’s process taxonomy modules are evaluated after costing of all the routing’s descendent operations.

Operation taxonomy modules are evaluated (if present) for each feasible operation in the context of a particular stock selection, process routing, machine selection, GCD, operation sequence, and tool selection. Costing proceeds in a bottom-up fashion; an operation’s taxonomy module is evaluated after costing of all the operation’s descendant operations. That way, an operation taxonomy module can access the results of the modules associated with its children in the process-operation hierarchy, in order, for example, to aggregate their costs.