Authorized representative filings must include authorization and office address before hearing; changes require intimation and special leave limits others. Regulation 13 requires that an authorized representative for the applicant or the Principal Commissioner or Commissioner file, before the commencement of the hearing, a document authorizing appearance and notify the Secretary of the address of his office; any change of authorized representative must be intimated to the Secretary and the other party, and no person other than the applicant, the concerned Principal Commissioner or Commissioner, or their authorized representative shall be heard in person except by special leave of the Authority.