((a)) An advance payment made on an order under is credited to a special working fund that the Secretary of the Treasury considers necessary to be established. Except as provided in this section, any other payment is credited to the appropriation or fund against which charges were made to fill the order.
((b)) An amount paid under may be expended in providing goods or services or for a purpose specified for the appropriation or fund credited. Where goods are provided from stocks on hand, the amount received in payment is credited so as to be available to replace the goods unless—
((1)) another law authorizes the amount to be credited to some other appropriation or fund; or
((2)) the head of the executive agency filling the order decides that replacement is not necessary, in which case, the amount received is deposited in the Treasury as miscellaneous receipts.
((c)) This section does not affect other laws about working funds.