1960's ford select-o-speed transmssion supplemental service manual

SOS is the distress signal of the International Morse Code. This distress signal was first adopted by the German government in radio regulations as of April 1, 1905 and became the world standard under the Second International Radiotelecratic Convention, signed on November 3, 1906. It entered In force on 1 July 1908. SOS continued to be the distress signal of the maritime radio until 1999, when it was replaced by the Global Maritime Distress and Safety System. SOS is still recognized as a visual distress signal.

The SOS distress signal is a continuous sequence of three dits, three dahs and three dits, all together without letter separation. In the International Morse Code, three dits form the letter S, and three dahs make the letter O, so "SOS" became an easy way to remember the order of dits and dahs. In modern terminology, SOS is a "procedural signal" of Morse or "prosign", and the formal way of writing it is with a bar above the letters: SOS.

In popular usage, SOS was associated with phrases like "Save Our Ship" or "Send Out Succor" or "Save our Soul". SOS is just one of several ways the combination might have been written; VTB, for example, would produce exactly the same sound, but SOS was chosen to describe this combination. SOS is the only sign of nine elements in Morse code, making it easier to recognize, since no other symbol uses more than eight elements