{i} (British) D-Notice, official notice that the government sends to newspapers or other publications asking them to hold back and not publish sensitive information in order to protect the country
A defence notice, formerly an official request to news editors not to publish or broadcast items on specified subjects for reasons of national security, replaced in 1993 with the DA-notice
in the UK, an official government request to a newspaper that it should not print certain information, for reasons of national security