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Prosigns for Morse code

Procedure signs or prosigns are shorthand signals used in 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.[1][2] 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 distinguished from common abbreviations, since prosigns have exact equivalent procedure words for use in radio telephony (voice).

Prosigns may be represented in printed material either by a sequence of dots and dashes, or by a sequence of letters, which, if sent without the normal inter-character spacing (concatenated), correspond to the prosign symbol.


Notation / representationsEdit

There are at least three methods used to represent Morse prosign symbols:

  1. Unique dot/dash sequences, e.g. (▄▄▄▄▄▄▄▄).
  2. Unique audible sounds, e.g. "Dahdidididah"
  3. Non-unique printed or written concatenated character groups, e.g. BT
    (When overlining is not available, the same characters can be written in angle brackets <BT> or with underlining BT.)

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.[3] The difference in the transmission is subtle, but the difference in meaning is gross. For example, the prosign AA (▄▄▄▄▄▄▄▄) has the same meaning as the voice procedure word UNKNOWN STATION, but the two separate letter prosign AA (▄▄▄▄▄▄▄▄▄▄) has the same meaning as the voice procedure word ALL AFTER, and is used to indicate that part of the previously transmitted message needs to be re-transmitted; the only difference between the Morse code prosigns is 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 "– –").[4] 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[2] or new section in a message heading.[4] 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.[4] Other prosigns are officially designated for both letters and prosigns, such as "+" and AR.[4]. Some genuinely have only one use, such as CT or KA (▄▄▄▄▄▄▄▄▄▄▄), the International Morse prosign that marks the start of a new transmission[4] or new message.[2]


In the early decades of telegraphy many operating efficiency improvements were incorporated into telegraph operations, including the introduction of Morse symbols known as procedure signs or prosigns. Prosigns were not defined by the inventors of Morse code, but were gradually introduced over time, and greatly improved the speed and performance of daily high-volume message handling operations.

Improvements to the legibility of formal written telegraph messages (telegrams) by means of white space formatting were thus supported by the creation of the additional new procedure symbols. Mastery of these special Morse code prosigns is an important part of becoming a fluent and efficient telegrapher/telegraphist.

Official International Morse code procedure signsEdit

The procedure signs below are compiled from the official specification for Morse Code, ITU-R M.1677, International Morse Code[5], while others are defined the International Radio Regulations, including ITU-R M.1170,[6] ITU-R M.1172[7], ITU-R M.1677-1[5], 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.

General-use procedure signs
Prosign Matching Voice Procedure Word Code Symbol Defined in Explanation
DE THIS IS FROM ▄▄▄▄▄▄▄ ITU-R M.1172[8] ITU-R M.1677-1[9] Used to preceded the name or other identification of the calling station.
AA UNKNOWN STATION ▄▄▄▄▄▄▄▄ International Code of Signals[10] 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". Also means "I have no messages for you."
R ROGER ▄▄▄▄▄ ITU-R M.1172[8] 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[9] Invitation to transmit after terminating the call signal. (e.g. ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄).
AR OUT ▄▄▄▄▄▄▄▄ ITU-R M.1172[8] ITU-R M.1677-1[9] End of transmission / End of message / End of telegram.[a]
(Same as EC "end copy", and character +. Replacement for K?.)[b]
CL CLOSING ▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8]
CQ CQ ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] General call to all stations
CP ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] General call to two or more specified stations
CS ▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] What is the name or identity signal of your station?
AS WAIT ▄▄▄▄▄ ITU-R M. 1170[12] ITU-R M.1172[8] ITU-R M.1677-1[9] "I must pause for a few minutes." Also means "I am engaged in a contact with another station [that you do not hear]; please wait quietly."[c]
AS AR WAIT OUT ▄▄▄▄▄▄▄▄▄▄▄▄▄ ACP 124 I must pause for a more than a few minutes.
VE Verified ▄▄▄▄▄ ITU-R M.1677-1[9] Message is verified.
QRS SPEAK SLOWER ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
WA WORD AFTER ▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8]
WB WORD BEFORE ▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8]
AA ALL AFTER ▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] The portion of the message to which I refer is all that follows the text ...
AB ALL BEFORE ▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] The portion of the message to which I refer is all that precedes the text ...
BN ALL BETWEEN ▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] The portion of the message to which I refer is all that falls between ... and ...
? SAY AGAIN ▄▄▄▄▄▄▄▄ ITU-R M.1677-1[9]ACP 124 When standing alone, a note of interrogation or request for repetition of a transmission not understood. When ? is placed after a signal, modifies the signal to be a question or request.
INT INTERROGATIVE ▄▄▄▄▄▄▄▄ ACP124[13], ACP131, Radiotelegraph Operations Guide[14] Military replacement for the ? prosign; equivalent to Spanish ¿ punctuation mark. When placed before a signal, modifies the signal to be a question/request.[d][15]


▄▄ ITU-R M.1677-1[9] Preceding text was in error. The following is the corrected text. (Same as EEEEEEEE.)
C CORRECT / AFFIRMATIVE ▄▄▄▄▄▄▄▄ ITU-R M.1172[8]
N NEGATIVE ▄▄▄▄▄ International Code of Signals[10] ACP 131 Answer to prior question is "no".[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[8] ITU-R M.1677-1[9] Same as character = or – –.
BK BREAK-IN ▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] Signal used to interrupt a transmission already in progress. AX in ACP131. In military networks TTTT is used instead.
KA ATTENTION ▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] ITU-R M.1677-1[9] Message begins / Start of work / New message
(Starting signal that precedes every transmission. Sometimes written as CT.)
CFM I ACKNOWLEDGE ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] Message received. (Same as R.)
WX ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ITU-R M.1172[8] Weather report follows


ITU-R M.1172[8] International Code of Signals groups follow

Morse code prosigns for message handling and formatting in Amateur Radio NTS netsEdit

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.

Table of Morse Code Prosigns and Useful Morse Code Abbreviations[1][4]
Prosign Code Symbol Meaning Comments Verbalization As text
AA ▄▄▄▄▄▄▄▄ Start new line Space down one line; typewritten as Carriage Return, Line Feed (CR-LF).[2] Also written RT. "didahdidah" Ä, Á[g]
AR ▄▄▄▄▄▄▄▄ Message separator, start new message / telegram.[4][1] New Page, space down several lines.[1] Decoder software may show "+".[4] Alternative for "Break" in conversational Morse.[2] Also written RN. "didahdidahdit" +[4]
AS ▄▄▄▄▄ Wait [4][1] Respond with: SN, or characters "R" (Received) or "C" (Confirmed).[1][4] "didahdididit" &[h]
BT ▄▄▄▄▄▄▄▄ Start of new section[4] / new paragraph.[1] Space down two lines; typewritten CR-LF-LF. Decoder software may show "="[4]. "dahdidididah" =, – – [4]
CT ▄▄▄▄▄▄▄▄▄▄▄ Start of transmission[4] Start of new message.[1] Attention[1] commencing transmission. Also written KA. "dahdidahdidah"  
HH ▄▄ Error / correction[4][1] Always followed by correct text.[1] Sometimes transcribed as "????". Sometimes written EEEEEEEE. "didididididididit"  
K ▄▄▄▄▄▄▄▄ Invitation for any station to transmit[4][1] Lone alphabetic character "K" at the end of a transmission.[1] "dahdidah" K[4]
? ▄▄▄▄▄▄▄▄ Please say again[4][1] Lone question mark "?" from the receiving station in response to a transmission.[1] "dididahdahdidit" ?[4][1]
KN ▄▄▄▄▄▄▄▄▄▄▄ Invitation for named station to transmit[1] Go ahead, specific named station.[1] Decoder software may show equivalent character "(".[4] "dahdidahdahdit" ( [4]
NJ ▄▄▄▄▄▄▄▄▄▄▄▄▄▄ Shift to Wabun code Shift from Morse code to Wabun code Kana characters. Also written XM. "dahdididahdahdah"  
SK ▄▄▄▄▄▄▄▄ End of contact[1] / End of work[4] Also written VA. "didididahdidah"  
SN ▄▄▄▄▄ Understood.[1] Verified.[4] Message received and checks okay. Alternatively shift from Wabun to Morse code. "SN?" verification requested. Also written VE. "didididahdit" Š, Ś[g]
SOS ▄▄▄▄▄▄▄▄▄▄▄ Start of distress signal[4][1] Only used by original message sender, and only for imminent danger to life or property.[4] (  listen ) "didididahdahdahdididit"  
BK ▄▄▄▄▄▄▄▄▄▄▄▄▄ Break in conversation[1] Morse abbreviation for "back-to you".[1] In conversational Morse some use either AR, BT, KN, or "K" instead. "dahdididitdadidah" BK
CL ▄▄▄▄▄▄▄▄▄▄▄▄▄ Closing down[1] Abbreviation for "closing station" (Morse abbreviation). "dahdidahditdidadidit" CL

Obsolete Morse code prosignsEdit

Historical Morse code prosigns
Prosign Matching Voice Procedure Word Former Code Symbol Explanation Defined in
VE General call ▄▄▄▄▄ 1937 Royal Navy Signal Card[16][17]
NNNNN Answering sign ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
ii Separative sign break ▄▄▄▄ Generally replaced by BT, although it is still used in MARS CW operations.[14] This prosign was also defined in ACP124, "Communication Instructions Radio Telegraph Procedure"[13]
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.

See alsoEdit

  • The ARRL Operations Manual.[1]
  • ARRL network reference page Sending Messages on CW.[2]


  1. ^ AR was used to mark the end of individual telegrams within a batched-message.
  2. ^ There is currently a proposal that (perhaps inadvertently) changes AR protocol. See ref [11]
  3. ^ AS may optionally be followed by the estimated number of minutes of waiting time.
  4. ^ 1945 procedural use: "The correctness of a short portion of a message may be questioned directly by the receiving operator using the interrogatory prosign INT, but this method should not be used to question a part of a message for which a receipt has been given.
  5. ^ When Morse was still being used in aeronautics, the entire word NO (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄) was sent instead of the abbreviation N.
  6. ^ The prowords HH AR may not be used to cancel a message after it has already been completely transmitted, and receipt acknowledged.
  7. ^ a b Non-ITU Code adopted nationally for languages with letters not used in Latin, English, or Italian.
  8. ^ Proposed double-use as punctuation AmperSand; non-standard. Abbreviation "E S" is typically used instead.


  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y ARRL Operating Manual (10 ed.). Newington, CT: American Radio Relay League. 8 October 2012. ISBN 978-0872595965. 
  2. ^ a b c d e f "Chapter 3: Sending Messages on CW" (PDF). ARRL network reference. Newington, CT: American Radio Relay League. 25 September 2002. 
  3. ^ "Miscellaneous abbreviations and signals to be used for radiocommunications in the Maritime Mobile Service". ITU Recommendations. Geneva, CH: International Telecommunications Union. ITU-R M.1172. 
  4. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa International Morse Code. ITU Recommendation. Geneva, CH: International Telecommunications Union. October 2009. ITU-R M.1677-1. 
  5. ^ a b "International Morse Code". ITU Recommendation. Geneva, CH: International Telecommunications Union. ITU-R M.1677-1. 
  6. ^ "Morse telegraphy procedures in the maritime mobile service" (PDF). ITU Recommendations. Geneva, CH: International Telecommunications Union. March 2012. ITU-R M.1170-1. 
  7. ^ "Miscellaneous abbreviations and signals to be used for radiocommunications in the maritime mobile service". ITU Recommendations. Geneva, CH: International Telecommunications Union. ITU-R M.1172. 
  8. ^ a b c d e f g h i j k l m n o p q r s t "Miscellaneous abbreviations and signals to be used for radiocommunications in the maritime mobile service". ITU Recommendations. Geneva, CH: International Telecommunications Union. ITU-R M.1172. 
  9. ^ a b c d e f g h i "International Morse Code". ITU Recommendations. Geneva, CH: International Telecommunications Union. ITU-R M.1677-1. 
  10. ^ a b "International Code of Signals" (PDF). (1969 (reaffirmed 2003) ed.). 
  11. ^ "Resolution on conflicting CW procedure" (PDF). 
  12. ^ "Morse telegraphy procedures in the maritime mobile service" (PDF). ITU Recommendations. Geneva, CH: International Telecommunications Union. ITU-R M.1170-1. 
  13. ^ a b "ACP124, Communication Instructions Radio Telegraph Procedure" (PDF). 
  14. ^ a b "Radiotelegraph Operations Guide" (PDF). 
  15. ^ United States War Department (1945). Radio Operator's Manual. Field Manual. Fort Monroe, VA: Army Field Printing Plant, CAS. FM24-6. 
  16. ^ "1937 Royal Navy Signal Card". 1937. 
  17. ^ "Signal Card".