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In Morse code, prosigns or procedural signals are special Morse code symbols (dot/dash sequences) that do not represent written alpha-numeric or punctuation text characters. Morse code prosign symbols are not generally part of the (written) information bearing characters of the text of a message. Instead, prosigns are special (unwritten) symbols, that have particular functions, such as: indicating changes of transmission communications protocol status, and indicating (or initiating) text or page ''white space'' formatting. These special Morse code prosign symbols, although preceding modern teleprinter (teletypewriter) and computer character sets by many decades, play a role in Morse code similar to that of the so-called (normally unprinted) control characters found in modern computer and teleprinter character set codes such as the: Baudot code (a.k.a. Murray code), ITA2, ASCII, UNICODE and EBCDIC codes. For over 140 years Morse code prosign symbols have been used by telegraphists, predating modern character set code control characters by many decades. Traditionally Morse code is manually sent (encoded) by operators (known as telegraphists) using hand operated telegraph keys and copied (decoded), either mentally, or by hand or typewriter, as the Morse code signals are received by ear in real time. Long before the advent of modern software and microprocessor based computer applications for encoding and decoding Morse code, the traditional Morse code prosign symbols were transmitted manually using telegraph keys, and duly recognized and acted upon when received by telegraphists. As with modern control characters Morse code prosigns are never explicitly written or printed, either by hand or by typewriter. Although seldom written, for illustrative purposes these Morse code prosign symbols may be shown or displayed explicitly in a ''special delimited written form'' as a related group of alphabetic Morse code characters that create the prosign symbol when ''run-together'' (concatenated) without inter-character spacing. This ''delimitation of run-together character groups'' representing Morse code prosigns is effected by ''special annotations'' applied to the (otherwise normal looking) character group for example as either: an over line extended over the character group as , or as angle brackets surrounding the character group as == Morse Prosigns and Modern Keyboards == Unlike modern ''fixed length'' symbol teleprinter and computer character set codes, such as the: Baudot code (a.k.a. Murray code), ITA2, ASCII, UNICODE and EBCDIC codes, Morse code uses bandwidth efficient ''variable length'' symbols sent by telegraphists using hand operated mechanical telegraph keys not by typing at teleprinter or computer keyboards. Although created without benefit of modern ''information theory'' concepts of Claude Shannon, the bandwidth efficiency of Morse code is readily understood in terms of Shannon's source coding (so-called data compression) techniques e.g ''Huffman coding'', etc. The keytops of modern teleprinter and computer keyboard keys are labeled with single alpha-numeric and punctuation characters plus a few other ''function keys'' that generate the corresponding ''fixed length'' alpha-numeric, punctuation or ''control character'' symbols when struck as dictated by the given character set code. ''Function keys'' generally represent non-written code symbols often labeled as: Alt, Ctrl, Enter, Shift, or f1, f2, f3... etc. or simply left unlabeled as is the so-called ''space bar'' function key. Striking a key on modern teleprinter and computer keyboards generates a single ''fixed length'' alpha-numeric, punctuation or control character and provides no capability to send run-together (concatenated) ''variable length'' symbols as required by traditional Morse code prosigns. Many of the built in ''control characters'' of the modern character set codes generated by keyboards are unrelated to the traditional ''variable length'' Morse code prosigns. Because of the fixed length character code symbols of modern keyboard operated devices, Morse code operators (telegraphists) may encounter difficulties when attempting to send traditional Morse code prosigns from a modern keyboard and may encounter incorrectly formed traditional prosigns that have been sent by keyboard Morse code operators. An example of the difficulties encountered by telegraphists using keyboards to send Morse code prosigns is the use of the key labelled "Enter" or "''Newline''" found on modern keyboards. Depending upon the application, striking the "Enter" or "''Newline''" key usually produces a result which is equivalent to the older Carriage return, Line Feed (CR-LF) sequence of actions which typists execute by hand on teleprinter or typewriter keyboards. The common multiple key Carriage return Line Feed (CR-LF) manipulations used with teleprinters and typewriters has the equivalent effect on printed text formatting as the single Morse code ''new line'' prosign Because of these teleprinter and computer keyboard Morse code software application limitations and omissions, it is difficult for operators sending Morse code from such keyboard controlled applications to create the traditional (unwritten) variable length Morse code prosigns. Some keyboard operators may work around this difficulty by connecting a standard telegraph key into the keying line along with the computer keyboard application and intervene during keyboard sending by manually using the standard telegraph key to transmit the traditional prosigns. This ''workaround'' however defeats the convenience of using a modern keyboard. Of course, none of these ''difficulties'' actually prevents software developers from developing Morse code application programs that enable full proper traditional Morse code prosign operations. One method might be utilizing modern computer keyboard ''function keys'' labeled: "f1", "f2", etc. to actuate traditional Morse code prosigns under program control. Apparently, because of the small commercial market for such applications, this currently does not seem to be the case. And so, Morse code keyboard operators may find that they are unable to properly send most traditional Morse code prosigns and sometimes may hear improperly formed (non-concatenated) prosigns sent by keyboard operated Morse code operators. Potential Morse code software application customers should heed the ancient Roman warning, ''caveat emptor'' when purchasing Morse code software application programs, and determine beforehand if the application handles Morse code prosigns appropriately! Nevertheless, as those who still enjoy sail boats in the age of power boats, fluent Morse code telegraphists will continue to enjoy sending Morse code and traditional Morse code prosigns using manually operated mechanical telegraph keys or electronic keyers. In order to become ''fluent'' telegraphists, aspiring Morse code operators must not only master the standard Morse code alpha-numeric and punctuation symbols but must also master the use of the traditional prosigns as described in the following table and paragraphs. Morse code prosigns are not dead yet. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prosigns for Morse code」の詳細全文を読む スポンサード リンク
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