For the purpose of this part—

(a) The term Department means the Department of the Treasury and includes the separate statutory agencies thereof.

(b) The term Director means the Director of Practice.

(c) The term General Counsel means the General Counsel of the Department.

(d) The term practice means any informal or formal appearance before, or, with the intent to influence, any oral or written communication to the Department or, where applicable, to a separate statutory agency thereof on a pending matter of business on behalf of any other person (except the United States).

(e) The term separate statutory agency thereof means an agency or bureau within the Department designated by rule by the Director, Office of Government Ethics, as a separate agency or bureau. The Internal Revenue Service, Bureau of Alcohol, Tobacco and Firearms, United States Secret Service, Bureau of the Mint, United States Customs Service, Bureau of Engraving and Printing, and Comptroller of the Currency were so designated effective July 1, 1979.