There shall be a statement of appeal, an answer thereto, and, if the appellant so elects, a reply to the answer. The appeal board may, at any time or from time to time, permit or require the filing of additional appeal papers, including supporting affidavits, memoranda or other papers, upon such terms and conditions as it may specify. All appeal papers must be typewritten, captioned to identify the appeal and addressed “To the Board of Education of the City of New York”.