# ACP 131 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/ACP_131 > Markdown URL: https://mediated.wiki/source/ACP_131.md > Source: https://en.wikipedia.org/wiki/ACP_131 > Source revision: 1332694998 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Defines Allied Military brevity codes}} {{More citations needed|date=February 2024}} {{Use dmy dates|date=September 2019}} '''ACP-131'''{{cite report |title=Communications Instructions Operating Signals |date=April 2009 |id=ACP 131(F) |publisher=[NATO](/source/NATO) [Combined Communications Electronics Board](/source/Combined_Communications_Electronics_Board) |url=http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F09.pdf |url-status=dead |via=jcs.dtic.mil |archive-url=https://web.archive.org/web/20130215140321/http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F09.pdf |archive-date=2013-02-15 }} is the controlling publication for the listing of {{nobr|[Q code](/source/Q_code)s}} and {{nobr|[Z code](/source/Z_code)s.}} It is published and revised from time to time by the [Combined Communications Electronics Board](/source/Combined_Communications_Electronics_Board) (CCEB) countries: Australia, New Zealand, Canada, United Kingdom, and United States. When the meanings of the codes contained in ACP-131 are translated into various languages, the codes provide a means of communicating between ships of various nations, such as during a [NATO](/source/NATO) exercise, where there is no common [language](/source/language). == History == The original edition of ACP-131 was published by the U.S. military during the early years{{when|date=September 2015}} of [radio](/source/radio) [telegraphy](/source/telegraphy) for use by [radio operator](/source/radio_operator)s using [Morse Code](/source/Morse_Code) on [continuous wave](/source/continuous_wave) (CW) telegraphy. It became especially useful, and even essential, to [wireless](/source/wireless) radio operators on both military and civilian ships at sea before the development of advanced [single-sideband](/source/single-sideband) [telephony](/source/telephony) in the 1960s. == Reason for the codes == Radio communications, prior to the advent of [landlines](/source/landline) and [satellite](/source/satellite)s as communication paths and relays, was always subject to unpredictable fade outs caused by [weather](/source/weather) conditions, practical limits on available emission power at the [transmitter](/source/transmitter), [radio frequency](/source/radio_frequency) of the transmission, type of emission, type of transmitting [antenna](/source/antenna_(radio)), [signal](/source/Signal_(electronics)) waveform characteristics, modulation scheme in use, sensitivity of the [receiver](/source/Receiver_(radio)) and presence, or lack of presence, of atmospheric reflective layers above the earth, such as the [E-layer](/source/E-layer) and [F-layer](/source/F-layer)s, the type of receiving antenna, the time of day, and numerous other factors. Because of these factors which often resulted in limiting periods of transmission time on certain frequencies to only several hours a day, or only several minutes, it was found necessary to keep each wireless transmission as short as possible and to still get the message through. This was particularly true of CW radio circuits shared by a number of operators, with some waiting their turn to transmit. As a result, an operator communicating by [radio telegraphy](/source/radio_telegraphy) to another operator, wanting to know how the other operator was receiving the signal, could send out a message on his key in [Morse Code](/source/Morse_Code) stating, "How are you receiving me?" :{{morse|dot|dot|dot|dot}} {{morse|dash|dash|dash}} {{morse|dot|dash|dash}} {{morse|word|dot|dash}} {{morse|dot|dash|dot}} {{morse|dot}} {{morse|word|dash|dot|dash|dash}} {{morse|dash|dash|dash}} {{morse|dot|dot|dash}} {{morse|word|dot|dash|dot}} {{morse|dot}} {{morse|dash|dot|dash|dot}} {{morse|dot}} {{morse|dot|dot}} {{morse|dot|dot|dot|dash}} {{morse|dot|dot}} {{morse|dash|dot}} {{morse|dash|dash|dot}} {{morse|word|dash|dash}} {{morse|dot}} {{morse|word|dot|dot|dash|dash|dot|dot}} Using ACP-131 codes, the question could be phrased simply "'''{{sc|{{overline|INT}} QRK}}'''" : {{morse|dot|dot|dash|dot|dash}} {{morse|word|dash|dash|dot|dash}} {{morse|dot|dash|dot}} {{morse|dash|dot|dash}} resulting in much more efficient use of circuit time. If the receiver hears the sender in a "loud and clear" condition, the response would be "'''{{sc|QRK 5}}'''": : {{morse|dash|dash|dot|dash}} {{morse|dot|dash|dot}} {{morse|dash|dot|dash}} {{morse|word|dot|dot|dot|dot|dot}} All of which requires less circuit time and less "pounding" on the key by the sending operators. Should the receiving operator not understand the sending operator, the receiving operator would send "'''{{sc|?}}'''" : {{morse|dot|dot|dash|dash|dot|dot}} or the marginally shorter '''{{sc|{{overline|INT}}}}''' : {{morse|dot|dot|dash|dot|dash}} The other operator would respond again with: : {{morse|dot|dot|dash|dot|dash}} {{morse|word|dash|dash|dot|dash}} {{morse|dot|dash|dot}}{{morse|dash|dot|dash}} which is much easier than retransmitting "How are you receiving me?" If the receiving operator understood the sending operator, the receiving operator would say the word "ROGER" or "MESSAGE RECEIVED", or the send the short form "'''{{sc|R}}'''" :{{morse|dot|dash|dot}} "'''{{sc|R}}'''" and "'''{{sc|?}}'''" are similarly structured, but very easy to distinguish. == Applicability of the codes == According to ACP-125(F), paragraphs 103 and 104, in radio communication among Allied military units: * Q codes are authorized for both civilian and military use, and for communications between the two. * Z codes are authorized for use only among military stations. :{|class="wikitable" |+ '''{{big|Applicability of codes by medium}}''' |- style="text-align:center;" ! Mil./Civ. !! Medium type !! Q codes? !! Z codes? |- style="text-align:center;" | Civilian || [continuous wave](/source/continuous_wave) radio (CW) || Q codes || |- style="text-align:center;" | Military || [continuous wave](/source/continuous_wave) radio (CW) || Q codes || Z codes |- style="text-align:center;" | Civilian || shipboard [signal lamp](/source/signal_lamp) || Q codes || |- style="text-align:center;" | Military || shipboard [signal lamp](/source/signal_lamp) || Q codes || Z codes |- style="text-align:center;" | Military || [flag semaphore](/source/flag_semaphore) || Q codes || Z codes |- style="text-align:center;" | Military || [teletype](/source/Teleprinter){{efn| Military [teleprinter](/source/teleprinter)s use Z codes for routing instructions in the message header. }} || || Z codes |} == Voice transmission == Some assert that the use of Q codes and Z codes was not intended for use on voice circuits, where plain language was speedy and easily recognizable, especially when employing the character recognition system in use at the time, such as ''ALPHA'', ''BRAVO'', ''CHARLIE'', ''etc''. However, in military communication the latter are still in use.Unclassified NATO naval-communication practices / manuals in Northern Europe {{full citation needed|date=September 2019}} A typical [simplex](/source/simplex_communication) military voice exchange: :{|class="wikitable" |- ! {{small|Sender → Receiver}} ! {{small|Question / response}} !style="text-align:left;"| Message |- style="text-align:center;" | '''C2 → L5''' | {{mvar|Q}} |style="text-align:left;"| {{mono| ''Lima'' five this is ''Charlie'' two: Radio check. Over. }} |- style="text-align:center;" | '''L5 → C2''' | {{mvar|R}} |style="text-align:left;"| {{mono| ''Lima'' five: ''Roger''. Over. }} |- style="text-align:center;" | '''C2 → L5''' | {{mvar|R}} |style="text-align:left;"| {{mono| ''Charlie'' two: ''Roger''. Out. }} |} However, some voice operators, such as [amateur radio](/source/amateur_radio) operators, find it convenient or traditional to carry over some of the Q codes to voice ("phone") exchanges, such as "QSL", "QRK", "QTH", ''etc''. == Footnotes == {{notelist}} == See also == {{div col begin|colwidth=30em}} * {{anl|500 kHz}} * {{anl|Continuous wave}} * {{anl|Morse code}} * {{anl|Q code}} * {{anl|Radio}} * {{anl|Z code}} {{div col end}} ==References== {{reflist}} == External links == * {{cite report |title=Communications Instructions Operating Signals |date=April 2009 |id=ACP 131(F) |publisher=[NATO](/source/NATO) [Combined Communications Electronics Board](/source/Combined_Communications_Electronics_Board) |url=http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F09.pdf |url-status=dead |via=jcs.dtic.mil |archive-url=https://web.archive.org/web/20130215140321/http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F09.pdf |archive-date=2013-02-15 }} * {{cite report |title=Authorized Abbreviations, Brevity Codes, and Acronyms |id=Army Regulation 310-50 |url=https://fas.org/irp/doddir/army/ar310-50.pdf |via=fas.org }} {{Two-way radio}} {{Telecommunications}} Category:Brevity codes Category:Military standardization Category:Military publications Category:Military radio systems Category:Amateur radio Category:Encodings Category:Maritime communication Category:History of radio --- Adapted from the Wikipedia article [ACP 131](https://en.wikipedia.org/wiki/ACP_131) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/ACP_131?action=history)). 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