(a) The application, statement or report, including all amendments and, where practicable, all papers and documents filed as a part thereof, shall be clear, easily readable and shall be typewritten, mimeographed, printed or prepared by any similar process which, in the opinion of the Commission, produces copies suitable for repeated photocopying and microfilming.

(b) If printed, the application, statement or report shall be in type not smaller than 10-point, roman type, at least two points leaded.

(c) All printing, mimeographing, typing or other markings shall be in black ink, except that debits in credit categories and credits in debit categories may be set forth in red or black ink, but shall in all cases be designated in such manner as to be clearly distinguishable as such on photocopies.