# Council Decision of 23 September 2013 on the security rules for protecting EU classified information (2013/488/EU), Division 31: Combination settings shall be committed to memory by the smallest possible number of individuals needing to know them. Combination settings for security containers and strong rooms storing EUCI shall be changed:

Extent: E+W+S+N.I.

(a) on receipt of a new container;
(b) whenever there is a change in personnel knowing the combination;
(c) whenever a compromise has occurred or is suspected;
(d) when a lock has undergone maintenance or repair; and
(e) at least every 12 months.

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Source: https://www.legislation.gov.uk/eudn/2013/488/annex/II/division/VI/division/31 (the official version)
Page: https://openlegislation.uk/eu-decision-2013-488/annex-II/division-VI/division-31
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.