The high-level logic of any cost model is specified by the cost engine algorithm (see Cost Engine Details). This part-costing algorithm specifies the flow of evaluation of the various types of CSL modules. For example, it specifies that each process’s machine selection module is evaluated only if its feasibility module evaluates to true. The code in a CSL module specifies the rules and formulas that make up a particular portion of a cost model, such as the portion that evaluates the feasibility of a particular process, or selects a machine for a process, or computes a process’s cost taxonomy.