All papers to be filed under the regulations in this part may be reproduced by printing or by any other process, provided the copies are clear and legible; shall be dated, the original signed in ink, and shall show the docket description and title of the proceeding, and the title, if any, and address of the signatory. If typewritten, the impression shall be on only one side of the paper and shall be double spaced, except that quotations shall be single spaced and indented. Documents not printed, except correspondence and exhibits, should be on strong, durable paper and shall not be more than 8 1/2 inches wide and 12 inches long, with a left margin 1 1/2 inches wide. Printed documents shall be printed in clear type (never smaller than pica or 11-point type) adequately leaded, and the paper shall be opaque and unglazed. Briefs, if printed, shall be printed on paper not less than 6 1/8 inches wide and 9 1/4 inches long, with inside margin not less than 1 inch wide. All briefs over 15 pages shall contain a subject index with page references and a list of authorities cited.