The party causing the first paper to be filed shall obtain an index number and communicate it forthwith to all other parties to the action. Thereafter such number shall appear on the outside cover and first page, to the right of the caption, of every paper tendered for filing in the action. Each such cover and first page also shall contain an indication of the county of venue and a brief description of the nature of the paper. In addition to complying with the provisions of CPLR 2101, every paper filed in court shall have annexed thereto appropriate proof of service on all parties where required, and if typewritten, shall have at least a double space between each line, except for quotations and the names and addresses of attorneys appearing in the action, and shall have at least one-inch margins. In addition, every paper filed in court, other than an exhibit or printed form, shall contain writing on one side only, except that papers that are fastened on the side may contain writing on both sides. Papers that are stapled or bound securely shall not be rejected for filing simply because they are not bound with a backer of any kind.
N.Y. Comp. Codes R. & Regs. Tit. 22 § 208.4