This subchapter provides for an efficient and uniform system of practice and procedure before the Commission. This subchapter governs the institution, conduct, and determination of adjudicative proceedings required or permitted by law, whether instituted by the Commission or by the filing of an application, claim, complaint, or any other pleading. This subchapter does not enlarge, diminish, modify, or otherwise alter the jurisdiction, powers, or authority of the Commission, the Executive Director, or the substantive rights of any person or agency.