10 January 1963: CAN-UK JCECS - US MCEB Methods and Procedures Panels Directive ACP 121 Communication Instructions - Message Precedence Categories

While there is less evidence that the Americans sought a hands-on relationship with the Canadians in the HYDRA move, they could also introduce a spanner in the works. In this report, the U.S. Military Communications Electronics Board proposed changes to ACP 121 procedures. These communication instructions were used by the NATO allies, and had 6 levels of precedence. In light of technological changes and new automatic message switching equipment, the Americans proposed a new precedence system with only 4 levels.