# Council Decision of 23 September 2013 on the security rules for protecting EU classified information (2013/488/EU), Division 13: When creating an EU classified document:

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

(a) each page shall be marked clearly with the classification level;
(b) each page shall be numbered;
(c) the document shall bear a reference number and a subject, which is not itself classified information, unless it is marked as such;
(d) the document shall be dated; and
(e) documents classified SECRET UE/EU SECRET or above shall bear a copy number on every page, if they are to be distributed in several copies.

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Source: https://www.legislation.gov.uk/eudn/2013/488/annex/III/division/II/division/4/division/13 (the official version)
Page: https://openlegislation.uk/eu-decision-2013-488/annex-III/division-II/division-4/division-13
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.