(a) Beef may only be entered as a product of a participating country if the importer makes a declaration to the Customs Service, in the form and manner determined by the Customs Service, that a valid export certificate is in effect with respect to the beef.

(b) To be valid, an export certificate shall:

(1) Be issued by or under the supervision of the government of the participating country;

(2) Specify the name of the exporter, the product description and quantity, and the calendar year for which the export certificate is in effect;

(3) Be distinct and uniquely identifiable; and

(4) Be used in the calendar year for which it is in effect.