SOS
In 1906, the second International Radiotelegraphic Convention was held in Berlin. This convention developed many Service Regulations to be added to the main agreement, which was signed on November 3, 1906, and became effective on July 1, 1908. Article XVI of the regulations adopted Germany's Notzeichen distress signal as the international standard, reading: "Ships in distress shall use the following signal: · · · — — — · · ·  repeated at brief intervals". The first ship to transmit an SOS distress call appears to have been the Cunard liner Slavonia on June 10, 1909, according to "Notable Achievements of Wireless" in the September, 1910 Modern Electrics. However, there was some resistance among the Marconi operators about adopting the new signal, and, as late as the April, 1912 sinking of the RMS Titanic, the ship's Marconi operators intermixed CQD and SOS distress calls. But with the need for consistency for public safety, the use of CQD appears to have generally disappeared after this point.