Procedure signs or prosigns are shorthand signals used in Morse code radio telegraphy procedures, for the purpose of simplifying and standardizing communications related to radio operating issues among two or more radio operators. They are distinct from general Morse code abbreviations, which consist mainly of brevity codes that convey messages to other parties with greater speed and accuracy.
There are also specialized variations used in radio nets to manage transmission and formatting of messages. In this usage, Morse prosigns play a role similar to the role played by the nonprinting control characters of teleprinter and computer character set codes such as Baudot or ASCII.
The development of prosigns began in the 1860s for wired telegraphy. They are distinct from common Morse abbreviations, in that they do not replace message content per se. Since Morse code communication preceded voice communications by several decades, many of the much older Morse prosigns have exact equivalent procedure words for use in the more recent radio telephony (voice).
In printed material describing their meaning and use, prosigns are represented by either a sequence of dots and dashes, or by an overlined sequence of letters, which, if sent without the normal inter-character spacing (concatenated), correspond to the prosign symbol.
In the early decades of telegraphy, many efficiency improvements were incorporated into operations. One of these was the introduction of Morse symbols called procedure signs or prosigns. Prosigns were not defined by the inventors of Morse code, but were gradually introduced to improve the speed and accuracy of high-volume message handling.
Improvements to the legibility of formal written telegraph messages (telegrams) using white space formatting were thus supported by the creation of procedure symbols. Mastery of these Morse code prosigns was important in becoming an efficient telegraph operator.
There are at least three methods used to represent Morse prosign symbols:
Although some of the prosigns as-written appear to be simply two adjacent letters, most prosigns are transmitted as digraphs that have no spacing between the patterns that represent the "combined" letters, and are most commonly written with a single bar over the merged letters (if more than one single character) to indicate this. The difference in the transmission is subtle, but the difference in meaning is gross. For example, the prosign AA (▄▄▄▄▄▄▄▄▄▄▄▄▄▄) indicates that the receiving Morse operator should space down one line, but the two separate letter sign or abbreviation AA (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄) indicates either the voice procedure words ALL AFTER, used to indicate that part of the previously transmitted message needs to be re-transmitted or has the same meaning as the voice procedure word UNKNOWN STATION. The difference in representation between the Morse code prosign and the separate letter signs is the presence or absence of an inter-letter space between the two "dot dash dot dash" sequences".
Because there are no letter boundaries in the transmitted prosigns, their division into letters is arbitrary and may be done in multiple equivalent ways. For example, AA (▄▄▄▄▄▄▄▄+▄▄▄▄▄▄▄▄) is exactly equivalent to EK (▄▄▄▄+▄▄▄▄▄▄▄▄▄▄▄▄) and RT (▄▄▄▄▄▄▄▄▄▄+▄▄▄▄▄▄). Likewise, the well-known prosign SOS could just as well be written VZE (▄▄▄▄▄▄▄▄▄▄▄▄+▄▄▄▄▄▄▄▄▄▄▄▄▄▄+▄▄▄▄), VGI (▄▄▄▄▄▄▄▄▄▄▄▄+▄▄▄▄▄▄▄▄▄▄▄▄+▄▄▄▄▄▄), or even 3B (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄+▄▄▄▄▄▄▄▄▄▄▄▄). Normally, one particular form is used by convention, but some prosigns have multiple forms in common use.
Many Morse code prosigns do not have written or printed textual character representations in the original source information, even if they do represent characters in other contexts. For example, when embedded in text the Morse code sequence ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ represents the "double hyphen" character (normally "=", but also "- -"). When the same code appears alone it indicates the action of spacing down two lines on a page in order to create the white space indicating the start of a new paragraph or new section in a message heading. When used as a prosign, there is no actual written or printed character representation or symbol for a new paragraph (i.e. no symbol corresponding to "¶"), other than the two-line white space itself.
Some prosigns are in unofficial use for special characters in languages other than English, for example "Ä" and AA, neither of which is part of the international standard. Other prosigns are officially designated for both letters and prosigns, such as "+" and AR, which marks the end of a message.[a] Some genuinely have only one use, such as CT or KA (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄), the International Morse prosign that marks the start of a new transmission or new message.
The procedure signs below are compiled from the official specification for Morse Code, ITU-R M.1677, International Morse Code, while others are defined the International Radio Regulations, including ITU-R M.1170, ITU-R M.1172, and the International Code of Signals, with a few details of their usage appearing in ACP-131, which otherwise defines operating signals, not procedure signals.
|Prosign||Matching voice procedure word||Code symbol||Defined in||Explanation|
|DE||THIS IS FROM||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172 ITU-R M.1677-1||Used to precede the name or other identification of the calling station (Morse abbr.).|
|AA||UNKNOWN STATION||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||International Code of Signals||Used for directional signaling lights, but not in radiotelegraphy.|
|NIL||NOTHING HEARD||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||General-purpose response to any request or inquiry for which the answer is "nothing" or "none" or "not available" (Morse abbr.). Also means "I have no messages for you."|
|R||ROGER||▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Means the last transmission has been received, but does not indicate the message was understood or will be complied with.|
|K||OVER||▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1677-1||Invitation to transmit after terminating the call signal. (e.g. ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄).|
|AR||OUT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172 ITU-R M.1677-1||End of transmission / End of message / End of telegram.[a]|
(Same as EC "end copy", and character +.)[b]
|CL||CLOSING||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Announcing station shutdown (Morse abbr.).|
|CQ||CQ||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||General call to any station (Morse abbr.).|
|CP||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||General call to two or more specified stations (Morse abbr.).|
|CS||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||What is the name or identity signal of your station? (Morse abbr.)|
|AS||WAIT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M. 1170 ITU-R M.1172 ITU-R M.1677-1||"I must pause for a few minutes."[c] Also means "I am engaged in a contact with another station [that you may not hear]; please wait quietly."|
|AS AR||WAIT OUT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ACP 124||I must pause for a more than a few minutes.|
|VE||Verified||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1677-1||Message is verified.|
|WA||WORD AFTER||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||(Morse abbr.)|
|WB||WORD BEFORE||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||(Morse abbr.)|
|AA||ALL AFTER||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||The portion of the message to which I refer is all that follows the text ... (Morse abbr.)|
|AB||ALL BEFORE||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||The portion of the message to which I refer is all that precedes the text ... (Morse abbr.)|
|BN||ALL BETWEEN||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||The portion of the message to which I refer is all that falls between ... and ... (Morse abbr.)|
|?||SAY AGAIN||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1677-1 ACP 124||When standing alone, a note of interrogation or request for repetition of a transmission not understood.
When ? is placed after a coded signal, modifies the code to be a question or request.|
|INT||INTERROGATIVE||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ACP124, ACP131, Radiotelegraph Operations Guide||Military replacement for the ? prosign; equivalent to Spanish ¿ punctuation mark. When placed before a signal, modifies the signal to be a question/request.[d]|
|▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1677-1||Preceding text was in error. The following is the corrected text. (Same as EEEEEEEE.)|
|C||CORRECT / AFFIRMATIVE||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Answer to prior question is "yes". (Morse abbr.)|
|N||NEGATIVE||▄▄▄▄▄▄▄▄||International Code of Signals ACP 131||Answer to prior question is "no". (Morse abbr.)[e]|
|ZWF||WRONG||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Your last transmission was wrong. The correct version is ...|
|HH AR||DISREGARD THIS TRANSMISSION; OUT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||The entire message just sent is in error, disregard it. (Same as EEEEEEEE AR.)[f]|
|QTR?||REQUEST TIME CHECK||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Time-check request. / What is the correct time?|
(Time is always UTC, unless explicitly requested otherwise, e.g. QTR HST ?)
|QTR||TIME||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||The following is the correct UTC in HHMM 24-hour format|
|BT||BREAK||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172 ITU-R M.1677-1||Start new section of message.|
Same as character = or - -.
|BK||BREAK-IN||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Signal used to interrupt a transmission already in progress (Morse abbr.). AX in ACP131. In military networks TTTT is used instead.|
|KA||ATTENTION||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172 ITU-R M.1677-1||Message begins / Start of work / New message|
(Starting signal that precedes every transmission. Sometimes written as CT.)
|CFM||I ACKNOWLEDGE||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Message received (Morse abbr.). (Same as R.)|
|WX||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||ITU-R M.1172||Weather report follows (Morse abbr.).|
|ITU-R M.1172||International Code of Signals groups follow (Morse abbr.).|
For the special purpose of exchanging ARRL Radiograms during National Traffic System nets, the following prosigns and signals can be used, but many of them do not have equivalents in any other definition of Morse code signals, including the ITU-R and Combined Communications Electronics Board telecommunications specifications.
|Prosign||Code Symbol||Meaning||Comments||Verbalization||As text|
|AA||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Start new line||Space down one line; typewritten as Carriage Return, Line Feed (CR-LF). Also written RT.||"didahdidah"||Ä, Á[g]|
|AR||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Message separator, start new message / telegram.||New Page, space down several lines. Decoder software may show "+". Alternative for "Break" in conversational Morse. Also written RN.||"didahdidahdit"||+|
|AS||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Wait ||Respond with: SN, or characters "R" (Received) or "C" (Confirmed).||"didahdididit"||&[h]|
|BT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Start of new section / new paragraph.||Space down two lines; typewritten CR-LF-LF. Decoder software may show "=".||"dahdidididah"||=, - - |
|CT||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Start of transmission Start of new message.||Attention commencing transmission. Also written KA.||"dahdidahdidah"|
|HH||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Error / correction||Always followed by correct text. Sometimes transcribed as "?". Sometimes written EEEEEEEE.||"didididididididit"|
|K||▄▄▄▄▄▄▄▄▄▄▄▄||Invitation for any station to transmit||Lone alphabetic character "K" at the end of a transmission.||"dahdidah"||K|
|?||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Please say again||Lone question mark "?" from the receiving station in response to a transmission.||"dididahdahdidit"||?|
|KN||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Invitation for named station to transmit||Go ahead, specific named station. Decoder software may show equivalent character "(".||"dahdidahdahdit"||( |
|NJ||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Shift to Wabun code||Shift from Morse code to Wabun code Kana characters. Also written XM.||"dahdididahdahdah"|
|SK||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||End of contact / End of work||Also written VA.||"didididahdidah"|
|SN||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Understood. Verified.||Message received and checks okay. Alternatively shift from Wabun to Morse code. "SN?" verification requested. Also written VE.||"didididahdit"||?, ?[g]|
|SOS||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Start of distress signal||Only used by original message sender, and only for imminent danger to life or property. (listen (help·info))||"didididahdahdahdididit"|
|BK||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Break in conversation||Morse abbreviation for "back-to you" (Morse abbr.). In conversational Morse some use either AR, BT, KN, or "K" instead.||"dahdididit dadidah"||BK|
|CL||▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Closing down||Abbreviation for "closing station" (Morse abbr.).||"dahdidahdit didadidit"||CL|
|Prosign||Matching Voice Procedure Word||Former Code Symbol||Explanation||Defined in|
|VE||General call||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Code re-used for "Message verified" or "Message understood" (see SN above).||1937 Royal Navy Signal Card|
|ii||Separative sign break||▄▄▄▄▄▄▄▄▄▄▄▄||Generally replaced by BT, although it is still used in MARS CW operations. This prosign was also defined in ACP124, "Communication Instructions Radio Telegraph Procedure"|
|EEEEE||Erase sign||▄▄▄▄▄▄▄▄▄▄▄▄||Exactly five dots (code for numeral 5). Replaced by EEEEEEEE (exactly eight, HH).|
|RRRRR||Receipt sign||?????????????????????????||Replaced by R.|
|e||Further message sign||▄▄▄▄▄▄▄▄▄▄▄▄▄▄||Re-purposed original ITU symbol for É not used in English.|