Within 30 days after the service of petitioner's papers, respondent commission shall file with the clerk of the court an original and nine copies and shall serve on petitioner three copies of respondent's brief. At the time respondent commission's brief is filed, respondent may file an original and nine copies, with proof of service of three copies upon petitioner, of an appendix of record materials not contained in the record filed by petitioner.
N.Y. Comp. Codes R. & Regs. Tit. 22 § 530.4