# Parliamentary Voting System and Constituencies Act 2011, Paragraph 7


(1) Every ballot paper must contain an appropriate security marking (the official mark).
(2) The official mark must be kept secret.
(3) The counting officer may use a different official mark for different purposes.

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Source: https://www.legislation.gov.uk/ukpga/2011/1/schedule/2/paragraph/7 (the official version)
Page: https://openlegislation.uk/parliamentary-voting-system-and-constituencies-act-2011/schedule-2/paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.