This subpart sets forth the rules which govern the issuance and application of advance rulings under Article 509 of the NAFTA and the procedures which apply for purposes of review of advance rulings under Article 510 of the NAFTA. Importers in the United States and exporters and producers located in Canada or Mexico may request and obtain an advance ruling on a NAFTA transaction only in accordance with the provisions of this subpart whenever the requested ruling involves a subject matter specified in §181.92(b)(6) of this part. Accordingly, the provisions of this subpart shall apply in lieu of the administrative ruling provisions contained in subpart A of part 177 of this chapter except where the request for a ruling involves a subject matter not specified in §181.92(b)(6).