Written requests pursuant to section 516, Tariff Act of 1930, as amended (19 U.S.C. 1516), for information as to the classification, appraised value and rate of duty imposed upon designated imported merchandise shall be submitted in triplicate to the Commissioner of Customs. [T.D. 70-181, 35 FR 13432, Aug. 22, 1970, as amended by T.D. 80-271, 45 FR 75642, Nov. 17, 1980]