D.C. Mun. Regs. tit. 1, r. 1-2201
In any proceeding before the Board, a person may appear on his or her own behalf or on behalf of any other person. Any person appearing before the Board other than on his or her own behalf may be required by the Board to establish his or her authority to act in a representative capacity.
In computing any period of time, calendar days shall be counted. When the last day of the period so computed is a Saturday, Sunday or legal holiday, the period shall run until the end of the next day which is neither a Saturday, Sunday nor legal holiday.
Except as otherwise provided by law, whenever an act is required to be done within a specified time, the period of time prescribed may, for good cause, be extended by the Board.
An applicant shall not be required to appear before the Board unless the application is opposed.
D.C. Mun. Regs. tit. 1, r. 1-2201