This part contains rules governing the recognition of attorneys, certified public accountants, enrolled agents, enrolled retirement plan agents, registered tax return preparers, and other persons representing taxpayers before the Internal Revenue Service. Subpart A of this part sets forth rules relating to the authority to practice before the Internal Revenue Service; subpart B of this part prescribes the duties and restrictions relating to such practice; subpart C of this part prescribes the sanctions for violating the regulations; subpart D of this part contains the rules applicable to disciplinary proceedings; and subpart E of this part contains general provisions relating to the availability of official records.