Pub. L. 84-1028, tit. 10, subtit. A, pt. II, ch. 55, sec. 1078
Instructions for marking ballots
§ 1078. Instructions for marking ballots (a) It is recommended that each State include in its instructions for absentee voting by the persons covered by section 1074 of this title an express instruction that the voter may mark his ballot by pencil, pen, crayon, or any other suitable method of showing his intention. If the laws of a State do not authorize such an instruction, it is recommended that they be amended to do so. (b) It is further recommended that each State express its voting instructions in simple terms, and not merely by quoting the pertinent statutes.