Procedure words (abbreviated to prowords) are words or phrases limited to radiotelephony procedure used to facilitate communication by conveying information in a condensed standard verbal format. [1] Prowords are voice versions of the much older procedural signs for Morse code which were first developed in the 1860s for Morse telegraphy, and their meaning is identical.
The NATO communications manual ACP-125 [2] contains the most formal and perhaps earliest modern (post-World War II) glossary of prowords, but its definitions have been adopted by many other organizations, including the United Nations Development Programme, [3] the U.S. Coast Guard, [4] US Civil Air Patrol, [5] US Military Auxiliary Radio System, [6] and others.
Prowords are one of several structured parts of radio voice procedures, including brevity codes and plain language radio checks.
According to the U.S. Marine Corps training document FMSO 108, "understanding the following PROWORDS and their respective definitions is the key to clear and concise communication procedures".
This transmission is from the station whose designator immediately follows. For clarity, the station called should be named before the station calling. So, "Victor Juliet zero, THIS IS Golf Mike Oscar three...", or for brevity, "Victor Juliet zero, Golf Mike Oscar three, ...". One can never say, "This is GMO3 calling VJ0".[ citation needed ]
"This is the end of my transmission to you and a response is necessary. Go ahead: transmit."
"Over" and "Out" are never used at the same time, since their meanings are mutually exclusive. With spring-loaded Push to talk (PTT) buttons on modern combined transceivers, the same meaning can be communicated with just "OUT", as in "Ops, Alpha, ETA five minutes. OUT."[ clarification needed ]
"This is the end of my transmission to you and no answer is required or expected."[ citation needed ]
A question about whether the receiver can hear and understand the transmission.
Example: "Bob, you read me? What is the situation from your position?"
Example:
"ROGER" may be used to mean "yes" with regard to confirming a command; however, in Air Traffic Control phraseology, it does not signify that a clearance has been given.[ citation needed ]
The term originates from the practice of telegraphers sending an "R" to stand for "received" after successfully getting a message. This was extended into spoken radio during World War II, with the "R" changed to the spelling alphabet equivalent word "Roger". [8] [9] [10] The modern NATO spelling alphabet uses the word "Romeo" for "R" instead of "Roger", and "Romeo" is sometimes used for the same purpose as "Roger", mainly in Australian maritime operations.[ citation needed ]
"Copy" does not have the same meaning as "roger". Copy is used in communications between stations and indicates to the sender that the information for the receiver has been received satisfactorily. Roger acknowledges receipt and conveys that the receiver intends to take action based on the information conveyed. [ citation needed ]
"I understand and will comply." It is used on receipt of an order. "Roger" and "Wilco" used together (e.g. "Roger, Wilco") are redundant, since "Wilco" includes the acknowledgement element of "Roger". [11]
"I have not understood your message, please SAY AGAIN". Usually used with prowords "ALL AFTER" or "ALL BEFORE". Example: radio working between Solent Coastguard and a motor vessel, call-sign EG 93, where part of the initial transmission is unintelligible.
Example:
At this juncture, Solent Coastguard would reply, preceding the message with the prowords "I SAY AGAIN":
The word "REPEAT" should not be used in place of "SAY AGAIN", especially in the vicinity of naval or other firing ranges, as "REPEAT" is an artillery proword defined in ACP 125 U.S. Supp-2(A) with the wholly different meaning of "request for the same volume of fire to be fired again with or without corrections or changes" (e.g., at the same coordinates as the previous round). [12]
"Please repeat the message you just sent me beginning after the word or phrase said after this proword."[ citation needed ]
Example:
At this juncture, Solent Coastguard would reply, preceding the message after "position" with the prowords "I SAY AGAIN":
"Please repeat the message you just sent me ending before the word or phrase said after this proword."[ citation needed ]
"Wait for some time."
"I must pause for a few seconds."[ citation needed ]
"I must pause for longer than a few seconds. I will call you back."
"Please repeat my entire transmission back to me."[ citation needed ]
"The following is my response to your READ BACK proword."[ citation needed ]
"I made an error in this transmission. Transmission will continue with the last word correctly sent."[ citation needed ]
"What is my signal strength and readability; how do you hear me?"[ citation needed ]
The sender requests a response indicating the strength and readability of their transmission, according to plain language radio check standards:
"5 by 5" is an older term used to assess radio signals, as in 5 out of 5 units for both signal strength and readability. Other terms similar to 5x5 are "LOUD AND CLEAR" or "Lima and Charlie". Example:
Similar example in shorter form:
If the initiating station (Alpha 12 in the example) cannot hear the responding station (X-ray 23 above), then the initiator attempts a radio-check again, or if the responder's signal was not heard, the initiator replies to the responder with "Negative contact, Alpha 12 OUT".
The following readability scale is used: 1 = bad (unreadable); 2 = poor (readable now and then); 3 = fair (readable, but with difficulty); 4 = good (readable); 5 = excellent (perfectly readable).
Example of correct US Army radio check, for receiver A-11 (Alpha 11) and sender D-12 (Delta 12):
International Telecommunication Union (ITU) Radio Regulations and the International Civil Aviation Organization (ICAO) Convention and Procedures for Air Navigation Services set out "distress, urgency and safety procedures".
On the radio, distress (emergency) and rescue usage takes precedence above all other usage, and the radio stations at the scene of the disaster (on land, in a plane, or on a boat) are authorized to commandeer the frequency and prohibit all transmissions that are not involved in assisting them. These procedure words originate in the International Radio Regulations.
The Combined Communications-Electronics Board (representing military use by Australia, Canada, New Zealand, United Kingdom and United States) sets out their usage in the Allied Communications Publications "ACP 135(F) Communications instructions Distress and Rescue Procedures". [13]
Mayday is used internationally as the official SOS/distress call for voice. It means that the caller, their vessel or a person aboard the vessel is in grave and imminent danger, send immediate assistance. This call takes priority over all other calls. [14]
The correct format for a Mayday call is as follows:
[The first part of the signal is known as the "call"]
Mayday, Mayday, Mayday,
This is (vessel name repeated three times, followed by call sign if available)
[The subsequent part of the signal is known as the "message"]Mayday (vessel name)
My position is (position as a lat-long position or bearing and distance from a fixed point)
I am (type of distress, e.g. on fire and sinking)
I require immediate assistance
I have (number of people on board and their condition)
(Any other information e.g. "I am abandoning to life rafts")Over
VHF instructors, specifically those working for the Royal Yachting Association, often suggest the mnemonic MIPDANIO for learning the message of a Mayday signal: mayday, identify, position, distress, assistance, number-of-crew, information, over.[ citation needed ]
In aviation a different format is used:
[First part of the message] Mayday, Mayday, Mayday
[Second part of the message] Callsign
[Third part of the message] Nature of the emergency
For example: "Mayday, Mayday, Mayday, Wiki Air 999, we have lost both of our engines due to a bird strike, we are gliding now."
After that pilot can give, or the controller can ask for, additional information, such as, fuel and number of passengers on board.
Pan-pan (pronounced /ˈpænˈpæn/ ) [15] is the official urgency voice call.
Meaning "I, my vessel or a person aboard my vessel requires assistance but is not in distress." This overrides all but a mayday call, and is used, as an example, for calling for medical assistance or if the station has no means of propulsion. The correct usage is:
Pan-Pan, Pan-Pan, Pan-Pan
All stations, all stations, all stations
This is [vessel name repeated three times]
My position is [position as a lat-long position or bearing and distance from a fixed point]
I am [type of urgency, e.g. drifting without power in a shipping lane]
I require [type of assistance required]
[Any other information e.g. size of vessel, which may be important for towing]Over[ citation needed ]
Pronounced /seɪˈkjuːrɪteɪ/ say-KURE-i-tay, this is the official safety voice call.
"I have important meteorological, navigational or safety information to pass on." This call is normally broadcast on a defined channel (channel 16 for maritime VHF) and then moved onto another channel to pass the message. Example:
[On channel 16]
SÉCURITÉ, SÉCURITÉ, SÉCURITÉ
All stations, all stations, all stations.
This is Echo Golf niner three, Echo Golf niner three, Echo Golf niner three.
For urgent navigational warning, listen on channel six-seven.
OUT
[Then on channel 67]
SÉCURITÉ, SÉCURITÉ, SÉCURITÉ
All stations, all stations, all stations.
This is Echo Golf niner tree (three), Echo Golf niner tree, Echo Golf niner tree.
Floating debris sighted off Calshot Spit.
Considered a danger to surface navigation.
OUT
"Seelonce" is an approximation rendition of the French word silence. Indicates that your vessel has an emergency and that you are requiring radio silence from all other stations not assisting you.
Indicates that you are relaying or assisting a station that has placed a MAYDAY call and you are requiring radio silence from all other stations not assisting you or the station in distress.
When the emergency issue is winding down and then has been resolved, these prowords are used to open up the frequency for use by stations not involved in the emergency:
From the French word prudence. Indicates that complete radio silence is no longer required and restricted (limited) use of the frequency may resume, but immediately giving way to all further distress communications.
From the French word silence and fini (ended). Indicates that emergency communications have ceased and normal use of the frequency may resume.
Proword | Meaning | Prosign/ OPSIG |
---|---|---|
ACKNOWLEDGE (ACK) | An instruction to the addressee that the message must be acknowledged | ZEV or QSL |
ADDRESS GROUP | The group that follows is an address group | |
ALL AFTER | The portion of the message to which I have reference is all that follows............... | AA |
ALL BEFORE | The portion of the message to which I have reference is all that precedes.............. | AB |
ANSWER AFTER | The station called is to answer after call sign........when answering transmissions. | ZGO |
ASSUME CONTROL | You will assume control of this net until further notice | ZKD |
AUTHENTICATE | The station called is to reply to the challenge that follows | INT ZNB |
AUTHENTICATION IS | The transmission authentication of this message is.......... | |
BREAK | I hereby indicate the separation of the text from other portions of the message | BT |
BROADCAST YOUR NET | Link the two nets under your control for automatic rebroadcast | |
CALL SIGN | The group that follows is a call sign | |
CLOSE DOWN | Stations are to close down when indicated. Acknowledgments are required | ZKJ |
CORRECT | You are correct, or what you have transmitted is correct. | C |
CORRECTION | An error has been made in this transmission. Transmission will continue with the last word correctly transmitted. An error has been made in this transmission (or message indicated). The correct version is...... That which follows is a corrected version in answer to your request for verification" | EEEEEEEE C C |
DISREGARD THIS TRANSMISSION – OUT | This transmission is in error, disregard it. (This proword shall not be used to cancel any message that has been completely transmitted and receipted.) | EEEEEEEE AR |
DO NOT ANSWER | Stations called are not to answer this call, receipt for this message, or otherwise transmit in connection with this transmission. When this proword is employed, the transmission shall be ended with the proword OUT. | F |
EXECUTE | Carry out the purport of the message or signal to which this applies. (To be used only with the Executive Method.) | IX----- |
EXECUTE TO FOLLOW | Action on the message or signal that follows is to be carried out upon receipt of the proword EXECUTE. (To be used only with the Delayed Executive Method.) | IX |
EXEMPT | The station(s) immediately following is (are) exempted from the collective call or from collective address | XMT |
FIGURES | Numerals or numbers follow. | |
FLASH | Precedence FLASH. | Z |
FROM | The originator of this message is indicated by the address designator immediately following | FM |
GRID | The portion following is a grid reference | |
GROUPS | This message contains the number of groups indicated by the numeral following. | GR |
GROUP NO COUNT | The groups in this message have not been counted. | GRNC |
I AM ASSUMING CONTROL | I am assuming control of this net until further notice | ZKA |
I AUTHENTICATE | The group that follows is the reply to your challenge to authenticate | ZNB |
IMMEDIATE | Precedence IMMEDIATE | O |
IMMEDIATE EXECUTE | Action on the message or signal following is to be carried out on receipt of the EXECUTE. (To be used only with the Immediate Executive Method.) | IX |
INFO | The addressees immediately following are addressed for information | INFO |
I READ BACK | The following is my response to your instructions to read back | IRB |
I SAY AGAIN | I am repeating transmission or portion indicated. | IMI |
I SPELL | I shall spell the next word phonetically. | |
I VERIFY | That which follows has been verified at your request and is repeated. (To be used only as a reply to VERIFY.) | C |
MESSAGE | A message that requires recording is about to follow. (Transmitted immediately after the call. This proword is not used on nets primarily employed for conveying messages. It is intended for use when messages are passed on tactical or reporting nets.) | ZBO |
MORE TO FOLLOW | Transmitting station has additional traffic for the receiving station. | B |
NEGATIVE (NEGAT) | No. Cancel message(s) sent by the Delayed Executive Method. (NEGAT may be used to cancel a single message or a group of messages awaiting execution.) | ZUG |
NET NOW | All stations are to net their radios on the unmodulated carrier wave that I am about to transmit. | ZRC2 |
NO PLAY | During exercises the words NO PLAY are used to distinguish real activity from messages concerned with exercise play e.g. a real emergency or real casualty. The first words of any message is to contain the words exercise (nickname e.g.Red Flag) NO PLAY | |
NOTHING HEARD | To be used when no reply is received from a call station. | ZGN |
NUMBER | Station serial number. | NR |
OUT | This is the end of my transmission to you and no answer is required or expected. | AR |
OVER | This is the end of my transmission to you and a response is necessary. Go ahead, transmit | K |
PRIORITY | Precedence PRIORITY | P |
READ BACK | Repeat this entire transmission back to me exactly as received | G |
REBROADCAST YOUR NET | Link the two nets under your control for automatic rebroadcast. | |
RELAY (TO) | Transmit this message to all addressees (or addressees immediately following this proword). The address component is mandatory when this proword is used. | T or ZOF |
RELAY THROUGH | Relay your message through call sign......... | ZOK |
ROGER | This is a method of receipt. I have received your last transmission satisfactorily. | R |
ROUTINE | Precedence ROUTINE. | R |
SAY AGAIN | Repeat all of your last transmission. Followed by identification data means "Repeat………… (portion indicated).” | IMI |
SEND YOUR | I am ready to receive your message, report, etc. | K |
(Used only in reply to the offer of a message, etc., on tactical or reporting nets.) | ||
SERVICE | The message that follows is a SERVICE message | SVC |
SIGNALS | The groups that follow are taken from a signal book. (This proword is not used on nets primarily employed for conveying signals. It is intended for use when tactical signals are passed on non-tactical nets.) | |
SILENCE (Repeated three or more times) | Cease transmissions on this net immediately. Silence will be maintained until lifted. (Transmissions must be authenticated by use of a self authenticated system, codeword, etc.) | HM HM HM |
SILENCE LIFTED | Silence is lifted. (Transmissions must be authenticated by means of self authentication system, codeword, etc.) | ZUG HM HM HM |
SPEAK SLOWER | Your transmission is too fast. Reduce speed of transmission. | QRS |
STOP REBROADCASTING | Cut the automatic link between the two nets that are being rebroadcast and revert to normal working. | |
THIS IS | This transmission is from the station whose designator immediately follows. | DE |
THIS IS A DIRECTED NET | From now until further notice this net is directed. | ZKB |
THIS IS A FREE NET | From now until further notice this net is free. | ZUG ZKB |
THROUGH ME | Relay your message through me | ZOE |
TIME | That which immediately follows is the time or datetime group of the message. | QTR |
TO | The addressees immediately following are addressed for action | TO |
--TO-- | The portion of the message to which I have reference is all that which appears between the groups.........and......... | |
UNKNOWN STATION | The identity of the station with whom I am attempting to establish communication is unknown. | AA |
USE ABBREVIATED CALL SIGNS | Call signs are to be abbreviated until further notice. | |
USE ABBREVIATED PROCEDURE | As conditions are normal, all stations are to use abbreviated procedure until further notice. | |
USE FULL CALL SIGNS | Call signs are to be sent in full until further notice | |
USE FULL PROCEDURE | As conditions are not normal, all stations are to use full procedure until further notice. | |
VERIFY | Verify entire message (or portion indicated) with the originator and send correct version. (To be used only at the discretion of, or by, the addressee to which the questioned message was directed.) | J |
WAIT | I must pause for a few seconds | AS |
WAIT – OUT | I must pause for longer than a few seconds. | AS AR |
WILCO | I have Received your signal, understand it, and will comply. To be used only by the addressee. Since the meaning of ROGER is included in that of WILCO, the two prowords are never used together. | |
WORD AFTER | The word of the message to which I have reference is that which follows.............. | WA |
WORD BEFORE | The word of the message to which I have reference is that which precedes.............. | WB |
WORDS TWICE | Communication is difficult. Transmit each phrase (or each code group) twice. (This proword may be used as an order, request, or as information.) | QSZ |
WRONG | Your last transmission was incorrect. The correct version is....... | ZWF |
More formally known as "Aeronautical Mobile communications", radio communications from and to aircraft are governed by rules created by the International Civil Aviation Organization. ICAO defines a very similar but shorter list of prowords in Annex 10 of its Radiotelephony Procedures (to the Convention on International Civil Aviation). Material in the following table is quoted from their list. [16] ICAO also defines "ICAO Radio Telephony Phraseology". [17]
Proword | Meaning | Notes |
---|---|---|
Acknowledge | Let me know that you have received and understood this message | |
Affirmative or Affirm | Yes. | |
Approved | Permission for proposed action granted. | |
Break | I hereby indicate the separation between portions of the message. | |
Break Break | I hereby indicate the separation between messages transmitted to different aircraft in a very busy environment | |
Cancel | Annul the previously transmitted clearance | |
Check | Examine a system or procedure | |
Cleared | Authorized to proceed under conditions specified. | |
Confirm | I request verification of: (clearance, instruction, action information). | |
Contact | Establish communications with... | |
Correct | True or Accurate | |
Correction | An error has been made in this transmission (or message indicated). The correct version is... | |
Disregard | Ignore | |
How Do You Read | What is the readability of my transmission | |
I say again | I repeat for clarity or emphasis. | |
Monitor | Listen out on (frequency) | Often used by terminal controllers when instructing the recipient to tune into a different frequency and listen in, but refrain from creating unnecessary radio traffic. |
Negative | "No" or "Permission not granted", or "That is not correct" or "Not capable" | |
Over | My transmission is ended, and I expect a response from you. | |
Out | This exchange of transmissions is ended and no response is expected. | |
Read Back | Repeat all, or the specified part, of this message back to me exactly as received. | |
Recleared | A change has been made to your last clearance and this new clearance supersedes your previous clearance or part thereof. | |
Report | Pass me the following information... | |
Request | I should like to know... | |
Roger | I have received all of your last transmission. | |
Say Again | Repeat all, or the following part, of your last transmission. | |
Speak Slower | Reduce your rate of speech | Normal rate of speech is to never exceed 100 words per minute. This rate is still too fast for most people to write or type, so SPEAK SLOWER means a significant drop. |
Standby | Wait and I will call you. | |
Unable | I cannot comply with your request, instruction, or clearance. | |
Wilco | I understand your message and will comply with it. | |
Words Twice | (As a request) Communication is difficult. Please send every word, or group of words, twice. | |
Marine radio procedure words follow from the ACP-125 definition, and those in the International Radio Regulations published by the ITU, and should be used by small vessels as their standard radio procedure. Beginning in 2001, large vessels, defined as being 500 gross tonnage or greater, the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers has required that a restricted and simplified English vocabulary with pre-set phrases, called Standard Marine Communication Phrases (SMCP), be used and understood by all officers in charge of a navigational watch. These rules are enforced by the International Maritime Organization (IMO). [18] The IMO describes the purpose of SMCP, explaining "The IMO SMCP includes phrases which have been developed to cover the most important safety-related fields of verbal shore-to-ship (and vice-versa), ship-to-ship and on-board communications. The aim is to get round the problem of language barriers at sea and avoid misunderstandings which can cause accidents." [19]
The SMCP language is not free-form like the standard radio voice procedures and procedure words. Instead, it consists of entire pre-formed phrases carefully designed for each situation, and watch officers must pass a test of their usage in order to be certified under international maritime regulations. For example, ships in their own territorial waters might be allowed to use their native language, but when navigating at sea or communicating with foreign vessels in their own territorial waters, they should switch to SMCP, and will state the switch over the radio before using the procedures. When it is necessary to indicate that the SMCP are to be used, the following message may be sent: "Please use Standard Marine Communication Phrases." "I will use Standard Marine Communication Phrases."
This article possibly contains original research .(June 2020) |
"Clear" is sometimes heard in amateur radio transmissions to indicate the sending station is done transmitting and leaving the airways, i.e. turning off the radio, but the Clear proword is reserved for a different purpose, that of specifying the classification of a 16-line format radio message as one which can be sent in the clear (without encryption), as well as being reserved for use in responding to the Radio Check proword to indicate the readability of the radio transmission.
"Confirm" or "yes" and sometimes shortened to Affirm is heard in several radio services, but is not listed in ACP-125 as a proword. In poor radio conditions Affirmative can be confused with Negative. Instead, the proword Correct is used.
Means "no", and can be abbreviated to Negat. Because over a poor quality connection the words "affirmative" and "negative" can be mistaken for one another (for example over a sound-powered telephone circuit), United States Navy instruction omits the use of either as prowords. [20] Sailors are instructed to instead use "yes" and "no".
Two helicopters, call signs "Swiss 610" and "Swiss 613", are flying in formation :
Anytime a radio call is made (excepting "standby", where the correct response is silence), there is some kind of response indicating that the original call was heard. 613's "Roger" confirms to 610 that the information was heard. In the second radio call from 610, direction was given. 613's "Wilco" means "will comply."
Reading back an instruction confirms that it was heard correctly. For example, if all 613 says is "Wilco", 610 cannot be certain that he correctly heard the heading as 090. If 613 replies with a read back and the word "Wilco" ("Turn right zero-niner-zero, Wilco") then 610 knows that the heading was correctly understood, and that 613 intends to comply.
The following is the example of working between two stations, EG93 and VJ50 demonstrating how to confirm information:
A radio net is three or more radio stations communicating with each other on a common channel or frequency. A net is essentially a moderated conference call conducted over two-way radio, typically in half-duplex operating conditions. The use of half-duplex operation requires a very particular set of operating procedures to be followed in order to avoid inefficiencies and chaos.
The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "INT" or suffixed it with the standard Morse question mark UD.
Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications.
SOS is a Morse code distress signal, used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line, to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. In International Morse Code three dots form the letter "S" and three dashes make the letter "O", so "S O S" became a common way to remember the order of the dots and dashes. IWB, VZE, 3B, and V7 form equivalent sequences, but traditionally SOS is the easiest to remember.
The Global Maritime Distress and Safety System (GMDSS) is a worldwide system for automated emergency signal communication for ships at sea developed by the United Nations' International Maritime Organization (IMO) as part of the SOLAS Convention.
The radiotelephony message PAN-PAN is the international standard urgency signal that someone aboard a boat, ship, aircraft, or other vehicle uses to declare that they need help and that the situation is urgent, but for the time being, does not pose an immediate danger to anyone's life or to the vessel itself. This is referred to as a state of "urgency". This is distinct from a mayday call, which means that there is imminent danger to life or to the continued viability of the vessel itself. Radioing "pan-pan" informs potential rescuers that an urgent problem exists, whereas "mayday" calls on them to drop all other activities and immediately begin a rescue.
A signal strength and readability report is a standardized format for reporting the strength of the radio signal and the readability (quality) of the radiotelephone (voice) or radiotelegraph signal transmitted by another station as received at the reporting station's location and by their radio station equipment. These report formats are usually designed for only one communications mode or the other, although a few are used for both telegraph and voice communications. All but one of these signal report formats involve the transmission of numbers.
Radiotelephony procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the armed forces, in civil aviation, police and fire dispatching systems, citizens' band radio (CB), and amateur radio.
From early in the 20th century, the radio frequency of 500 kilohertz (500 kHz) was an international calling and distress frequency for Morse code maritime communication. For much of its early history, this frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles or 500 kc.
In telecommunications, radio silence or emissions control (EMCON) is a status in which all fixed or mobile radio stations in an area are asked to stop transmitting for safety or security reasons.
Procedural signs or prosigns are shorthand signals used in Morse code telegraphy, for the purpose of simplifying and standardizing procedural protocols for landline and radio communication. The procedural signs are distinct from conventional Morse code abbreviations, which consist mainly of brevity codes that convey messages to other parties with greater speed and accuracy. However, some codes are used both as prosigns and as single letters or punctuation marks, and for those, the distinction between a prosign and abbreviation is ambiguous, even in context.
A radiogram is a formal written message transmitted by radio. Also known as a radio telegram or radio telegraphic message, radiograms use a standardized message format, form and radiotelephone and/or radiotelegraph transmission procedures. These procedures typically provide a means of transmitting the content of the messages without including the names of the various headers and message sections, so as to minimize the time needed to transmit messages over limited and/or congested radio channels. Various formats have been used historically by maritime radio services, military organizations, and Amateur Radio organizations.
APRS Calling is a manual procedure for calling stations on the Automatic Packet Reporting System (APRS) to initiate communications on another frequency, or possibly by other means. It is inspired by Digital Selective Calling, a part of the Global Maritime Distress Safety System. It also builds on existing digital procedures inherited from morse code and radioteletype operation. ITU Q codes are used in conjunction with APRS text messages to implement APRS calling. APRS calling is intended to complement monitoring voice calling frequencies.
A plain-language radio check is the means of requesting and giving a signal strength and readability report for radiotelephony (voice) communications, and is the direct equivalent to the QSA and QRK code used to give the same report in radiotelegraph communications. SINPEMFO code is the voice signal reporting format developed by the ITU in 1959, but sees little use outside of shortwave listeners.
16-line message format, or Basic Message Format, is the standard military radiogram format for the manner in which a paper message form is transcribed through voice, Morse code, or TTY transmission formats. The overall structure of the message has three parts: HEADING, TEXT, and ENDING. This heading is further divided into procedure, preamble, address, and prefix. Each format line contains pre-defined content. An actual message may have fewer than 16 actual lines, or far more than 16, because some lines are skipped in some delivery methods, and a long message may have a TEXT portion that is longer than 16 lines by itself.
The QSA code and QRK code are interrelated and complementary signal reporting codes for use in wireless telegraphy. An enhanced format, SINPO code, was published in the ITU Radio Regulations, Geneva, 1959, but is longer and unwieldy for use in the fast pace of Morse code communications.
ACP 125 is the short name for Allied Communications Publication 125: Communications Instructions—Radiotelephone Procedures, developed and published by the Combined Communications Electronics Board, for use by the Five Eyes nations and the rest of NATO. According to the latest version,
"The aim of ACP 125 is to prescribe the voice procedure for use by the armed forces of Allied nations on secure and non-secure tactical voice nets. Its purpose is to provide a standardized way of passing speech and data traffic as securely as possible consistent with accuracy, speed and the needs of command and control."
Allied Communication Procedures is the set of manuals and supplements published by the Combined Communications Electronics Board that prescribe the methods and standards to be used while conducting visual, audible, radiotelegraph, and radiotelephone communications within NATO member nations. These procedures relate to procedure words, radiotelephony procedure, Allied Military phonetic spelling alphabets, plain language radio checks, the 16-line message format (radiogram), and others.
Time synchronization over radio is the procedure used for time transfer performed by humans over two-way radio circuits, including voice, telegraph, and teletype.
Allied Communications Publications are documents developed by the Combined Communications-Electronics Board and NATO, which define the procedures for communicating in computer messaging, radiotelephony, radiotelegraph, radioteletype (RATT), air-to-ground signalling, and other forms of communications used by the armed forces of the five CCEB member countries and/or NATO.
Distress communications have absolute priority over all other transmissions.