19 CFR § 10.174 - Evidence of direct shipment.
(a) Documents constituting evidence of direct shipment. The Center director may require that appropriate shipping papers, invoices, or other documents be submitted within 60 days of the date of entry as evidence that the articles were “imported directly”, as that term is defined in § 10.175. Any evidence of direct shipment required by the Center director shall be subject to such verification as he deems necessary.
(b) Waiver of evidence of direct shipment. The Center director may waive the submission of evidence of direct shipment when he is otherwise satisfied, taking into consideration the kind and value of the merchandise, that the merchandise clearly qualifies for treatment under the Generalized System of Preferences.