It is requested that no details be published, without prior consultation, of the British Government's highly classified codes and ciphers, related data protection measures and communication facilities, or those of NATO or other allies.

It is also requested that advice be sought before disclosing, or elaboration on, information published at home or overseas about UK official codes and ciphers or their potential vulnerability.

Rationale. Disclosures that could compromise codes and ciphers put at risk the classified information protected by them and, indirectly, people’s lives. Revealing details of associated data protection measures and communications facilities, whether obtained, for example, from documents or by techniques such as computer hacking, could assist potential enemies to penetrate these elements of national security.