American Morse code standard for U.S. landline telegraph companies, including the dominant company, Western Union, in part because the original code, with fewer dashes, could be sent about 5% faster than International Morse. American Morse also was commonly used for domestic radio transmissions on the Great Lakes, and along the Atlantic and Pacific coasts. However, International Morse predominated for ocean-going vessels, and many U.S. shipboard operators became skilled in transmitting both versions of the Code as needed. As already mentioned, American Morse is less suitable for use on cables because of the high density of dots. However, this same feature, together with the
Morse code bands are reserved for transmission of Morse code signals only. The relatively limited speed at which Morse code can be sent led to the development of an extensive number of abbreviations to speed communication. These include prosigns, Q codes, and a set of Morse code abbreviations for typical message components. For example, CQ is broadcast to be interpreted as "seek you" (I'd like to converse with anyone who can hear my signal). OM (old man), YL (young lady) and XYL ("ex-YL" – wife) are common abbreviations. YL or OM is used by an operator when referring to the other operator,