Morse code become commonly available until around 1920. Until 2003, the International Telecommunication Union mandated Morse code proficiency as part of the amateur radio licensing procedure worldwide. However, the World Radiocommunication Conference of 2003 made the Morse code requirement for amateur radio licensing optional. Many countries subsequently removed the Morse requirement from their licence requirements. Until 1991, a demonstration of the ability to send and receive Morse code at a minimum of five words per minute (wpm) was required to receive an amateur radio license for use in the United States from the Federal Communications Commission. Demonstration of this ability was still
Morse code abbreviations head, instead of writing text on paper or into a computer file, the receiving operator copying mentally will interpret the prosign for either a mental pause, or to jot down for later reference a short word or phrase from the information being sent. "Rag chewer" is a name applied to amateur radio Morse code operators who engage in informal Morse code conversations (known as "chewing the rag") while discussing subjects such as: the weather, their location, signal quality, and their equipment. Meaningful rag chewing between fluent Morse code operators having different native languages is possible because of a common language