(a) Rate proceeding means a proceeding involving the determination and prescription of any rate or charge made or proposed to be made for any stockyard service furnished at a stockyard by a stockyard owner or market agency, or a proceeding involving any rule, regulation or practice affecting any such rate or charge; and

(b) Administrator means the Administrator of the Grain Inspection, Agricultural Marketing Service (AMS), or any officer or employee of AMS to whom authority has heretofore been delegated, or to whom authority may hereafter be delegated, to act for the Administrator.