aPriori costs a part based on the logic provided by the cost engine, templates, and CSL modules, together with the data provided by the part’s geometry, production information (such as material selection), and cost model data (such as machine and material attributes). This chapter covers the management of cost model data with the CMWB, including management of cost model metadata, which provides the schema or definition (attribute names, types, default values, and so on) for cost model data.