Editing SOS (section)

==="Mayday" voice code===
With the development of audio radio transmitters, there was a need for a spoken distress phrase, and "[[Mayday]]" (from [[French language|French]] {{lang|fr|m'aider}} "help me") was adopted by the 1927 International Radio Convention as the spoken equivalent of SOS.<ref>{{cite web |title=Distress call |year=1927 |series=International Radiotelegraph Convention |place=Washington, DC |page=51 |via=hathitrust.org |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015016418306&view=1up&seq=57}}</ref> For "TTT", the equivalent spoken signal is "[[Sécurité]]" (from French {{Lang|fr|sécurité}} "safety") for navigational safety, while "[[Pan-pan]]" (from French {{lang|fr|panne}} "breakdown"; Morse "XXX") signals an urgent but not immediately dangerous situation.<ref>{{cite web |title=Urgent signal |year=1927 |series=International Radiotelegraph Convention |place=Washington, DC |page=54 |via=hathitrust.org |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015016418306&view=1up&seq=60}}</ref>