DoD conduct a comprehensive study of DBOF and present its findings along with a proposed improvement plan to Congress for approval. In December 1996, DBOF was reorganized into four working capital funds (Army, Navy, Air Force, and Defense-Wide). With the addition of a fifth fund—the Defense Commissary Agency in 1999—the new organization was now officially called the Defense Working Capital Fund (DWCF). The five funds and their corresponding business areas provide goods and services to DoD and authorized non-DoD activities. DWCF and NWCF operations The support functions financed through the NWCF, as part of the DWCF, are grouped together at the DWCF level into business areas that are managed within DoD. Business areas receive their initial working capital through an appropriation or transfer of resources from an existing revolving fund. This working capital is called the "corpus" and is used to finance the initial costs of goods and services. Resources to replenish the corpus are generated by acceptance of customer orders. Customer orders are obligations on the appropriations of the ordering activity. The business area delivers the goods or services ordered using the funds in the corpus, and then bills the customer based on the rates set for those goods and services. The fund is replenished when the customer pays the bill to the fund. Customer orders accepted by the NWCF activities must be either obligations of a federal government activity or cash advances from non-federal government customers. The acceptance of a customer order creates a quasi-contractual relationship between the NWCF activity and its customer. The customers of each NWCF activity are responsible for budgeting for and budgetary control of the cost of end products and services ordered from the NWCF activity. The customer cannot use its appropriated funds to do indirectly (through the NWCF activity) what it is not permitted to do directly. The availability of an appropriation cannot be expanded or otherwise changed by transfer to the NWCF. The customer bears the primary responsibility for the determination of the applicability of its appropriated funds in the orders placed with the NWCF activity. Stabilized billing rates One of the features of the NWCF that allows its customers to accurately plan and budget their appropriated funds for NWCF support requirements is the rate stabilization policy adopted by the NWCF. For each budget year, the NWCF establishes customer rates on an end product basis whenever feasible. These rates are set at