Computed value.
When the port director determines that information as to computed value is necessary in the appraisement of any class or kind of merchandise, he shall so notify the importer, and thereafter invoices of such merchandise shall contain a verified statement by the manufacturer or producer of computed value as defined in 402(e), Tariff Act of 1930, as amended by the Trade Agreements Act of 1979 (19 U.S.C. 1401a(e)).