# The Local Elections (Principal Areas) (England and Wales) Rules 2006, Paragraph 18: The official mark


(1) Every ballot paper must contain an appropriate security marking (the official mark).
(2) The official mark must be kept secret, and an interval of not less than five years shall intervene between the use of the same official mark at elections for the same county, ... district or London borough, as the case may be.
(3) The returning officer may use a different official mark for different purposes at the same election.

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Source: https://www.legislation.gov.uk/uksi/2006/3304/schedule/2/paragraph/18 (the official version)
Page: https://openlegislation.uk/local-elections-principal-areas-england-and-wales-rules-2006/schedule-2/paragraph-18
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.