D.C. Mun. Regs. tit. 7, § 2526
2526.1 The petition shall state briefly and specifically the matters of record alleged to have been erroneously decided, the ground relied upon, and the relief sought.
2526.2 If the petition is based in whole or in part on new matter, this shall be set forth in an affidavit and accompanied by a statement to the effect that the petitioner could not, with due diligence, have known or discovered the new matter prior to the date the case was presented to the Board for decision.