In assemble to order (ATO) environments, the available standard set of product attributes that will be combined to create the finished product. For example, in configuring a desktop computer, available features might include monitor size, hard drive size, CPU speed, and bundled software, among others. The options are the individual choices within the feature categories, such as a 5, 10 or 20 GB hard drive. The options usually can only be selected from a predefined menu, and when combined create the final customer selling price and cost to the manufacturer.