* Baudot code is what teletypes use. Each of the 32 characters in the teletype alphabet has a unique number assigned to it. This number can be represented as a five-digit binary number, that is, five ones or zeroes, or (more useful) five holes, or absences of holes, across a strip of paper tape. Such numbers can also be represented as patterns of electrical voltages, which can be sent down a wire, or over the radio waves, and printed out at the other end. Lately, the Germans have been using encrypted Baudot-code messages for communications between high-level command posts; e.g., between Berlin and the various Army group headquarters. At Bletchley Park, this category of encryption schemes is called Fish, and the Colossus machine is being built specifically to break it.