Abstract: An integrated MRP system for distributors, manufacture and job shops is provided. The MRP system of the present invention is specifically directed to an user which manufactures and sells products that have a wide variety of options. In particular, the MRP system of the present invention provides two key features. The first feature allows the user to define items which uniquely characterize the product for a customer order, purchase order, to work order. The second unique feature of the MRP system of the present invention is the application of user-defined formulas which allow the user to include user-defined formulas which determined the quantity and/or size of a part based on the selected options. Thus, the MRP system of the present invention allows the user who manufactures and sells a number of styles with a wide variety of options to employ an MRP system without a correspondingly high manintenance overhead.