The CCITT, unanimously declares that when it is necessary to provide for switching of telegrams to different routes in semi-automatic or fuiiy automatic telegram retransmission systems, the beginning and ending of each telegram are identified by the insertion of start-of-message and end-of-message signals; the start-of-message signal consists of the sequence ZCZC in letter case; the end-of-message signal consists of the sequence NNNN, in letter case.