The correspondence clerk shall note in red ink, on the face of each issue, immediately below the register number, the serial number of the major head, the minor head and the case file to which it belongs, and enter other details in column 7 of the correspondence register. If the letter or memorandum be eventually placed in a personal file or a bundle file under Rule 614 or 615, infra, he shall write "P.F." or "B.F." below the register number.
