Art. 54 Radioreglement 1979, Selective calling
54.1 § 1 1) Selective calling is designed for automatic station calling and distress alerting or the transmission of information for the organization of traffic.
54.2 2) Selective calling is carried out using a digital selective-calling system which shall be in accordance with Recommendation ITU-R M.541-11, and may be in accordance with the most recent version of Recommendation ITU-R M.493. (WRC-23)