(a) Number of copies and where filed. All petitions pursuant to section 516 Tariff Act of 1930, as amended (19 U.S.C. 1516), shall be submitted to the Commissioner of Customs in triplicate.

(b) By whom filed. Petitions may be filed by the domestic interested parties themselves, or by duly authorized attorneys or agents on their behalf. A petition filed by a corporation shall be signed by an officer thereof, and petition filed by a partnership shall be signed by a member thereof.