. . . - - - . . .

The Smithsonian reports:

"The International Radiotelegraphic Convention adopts three dots, three dashes and three dots - SOS in Morse code - as the standard wireless distress signal, on November 3rd, 1906. Chosen because it is easy to send and hard to misinterpret, the signal, which doesn't actually stand for anything - not even Save Our Ship - can't save the Titanic, which sends out SOSs in 1912. In 1999 a global satellite system replaces SOS on all large ships"