The recommended procedure for conducting Morse radiotelegraph communications is detailed in the most recent version of Recommendation ITU-R M.1170. (WRC-07)
Radio Regulations
Source: the Radio Regulations published by the International Telecommunication Union (ITU).
ART
55
Morse radiotelegraphy
RR-2024 · in force
CHAPTER IX — Maritime services
Source: ITU Radio Regulations, editions of 2008, 2012, 2016, 2020 and 2024. The English, French and Spanish texts are each taken from the official edition in that language, not translated from one another. Sources and citation.