Paragraph 7 The official mark
(1)
Every ballot paper shall have an official mark, which shall consist of—
(a)
a watermark;
(b)
feint printing which appears to lie behind the text of the ballot paper;
(c)
heat sensitive marks on the paper; or
(d)
distinctive paper.
(2)
The official mark shall be kept secret, and an interval of not less than five years shall intervene between the use of the same official mark at a referendum for the same referendum area or part of that area.
(3)
At combined polls the official mark for the referendums may be the same.