Starting off in 1890, we take a look back at the history of secret radio transmissions, leading up until today and unravel some of the mystery, whilst uncovering some new oddities, of what are known as ‘Numbers Stations’.

Competition is now closed, but here is the one time pad in case anyone wants to mess with it anyhow.

KiwiSDR – A web-based shortwave radio that you can use to hunt your very own station. Pick a radio from one of the locations and control via clicking on the spectrometer. You’ll find most stations sitting in the LSB band. – You’ll find station listings, schedules, well, basically you can find a whole horde of information on both current and historical stations. Also active in all sorts of radio shenanigans, such as their recent mapping of the DPRK’s diplomatic modem network.

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Shortwave radio broadcasts, originating from unknown locations, intended for unknown persons, yet easily accessible by anyone. These signals, containing coded messages have intrigued for decades. What are they for? Who is listening? And why, in the modern age, is such an archaic form of communication still being used? Mysterious, nonsensical, garbled and yet somehow beautiful, numbers stations pass through our airwaves, transmitting to no one. This is Dark Histories, where the facts are worse than fiction.

A Brief history of Radio Intelligence

The history of Radio used by military and government bodies is surprisingly long, with the British using radio signals for basic military communication even before the outbreak of the first world war. During the Boer wars, in the 1890s, the British Navy used limited wireless signalling onboard their ships. Since they were the only country using radio at the time, there was no need for any special cryptographical techniques to be used and no complicated equipment to either send or receive signals. The Russians soon hopped on board, their navy too begun to utilise radio signals around the turn of the 20th century, as they prepared to enter conflict with Japan. At that time, both British naval vessels alongside the Japanese, maintained listening stations on board ships to listen in to the Russians naval plans, birthing the concept of listening stations and counter-intelligence.

It was during the first world war however, that signal intelligence, or SIGINT as it was known, became a critical part of warfare. The concept of coding signals and sending them through the airwaves matured greatly and the British developed complex systems to both relay their own information to allies in the field and to listen in on their enemies transmissions. One of the first acts carried out upon the declaration of war with Germany in 1914, was to order British cable ships cut all undersea communication cables connecting England to Germany, this forced the German military to use radio to communicate across mainland Europe and after a short time and a little prodding in the right direction from amateur radio enthusiasts, the British military made themselves well placed to intercept such transmissions. By the end of 1914, British intelligence had set up a ramshackle group of listening posts, consisting of a single military station in Stockton-on-Tees and several installations belonging to the post office. Personnel consisted of military operators as well as private and civilian individuals from Marconi, a British telecommunications company and a small group of well-off private individuals who owned radio equipment. This was to later become known as “Y Service”, a government ran, communication listening and code decryption agency. For the most part, the services main role was to intercept and file messages sent from German military and direction finding duties, however with the sinking of a German Destroyer in October of 1914 and the retrieval of a codebook, known as the Verkehrsbuch Codebook, signal intelligence stepped up a gear.

The Verkehrsbuch Codebook was used to decode messages sent daily by the German navy to give position and route of every German ship currently at sea. This led to several large turning points of the war pivoting on radio intelligence espionage, securing its importance in warfare.

In 1919, after the end of the war, Britain set up a secret code breaking agency named GC&CS, the Government Code and Cypher School and spent the majority of the 1920’s deciphering Soviet Russian diplomatic communications. By 1940, this had broadened to an operation covering the transmissions of 26 countries. The German government also set up a code breaking signal intelligence service in the mid-1920s under Hermann Goering’s direction, and the US had by this time, also begun similar operations, though it’s agency, named the US Cipher Bureau was closed down in 1929 by the Secretary of War, Henry L Stimson, who claimed “Gentleman do not read each other’s mail.” Whilst this sentiment was, perhaps, well meaning, it was a crucial oversight and by the mid 1930’s, as tensions between the US and the Japanese rose, the practice of “reading anothers mail” begun anew. By the early 1940’s, all pretense was pushed to the wayside by the American government, as the importance became apparent and the British military begun supplying the US military with radio equipment, training them how to best utilise it for espionage activities, gentleman be damned.

As war broke out across Europe in The Second World War, British intelligence moved all signal intelligence activities within GC&CS to the now infamous Bletchley Park, in Milton Keynes, Buckinghamshire. Bletchley Park  became the centre for all code breaking activities throughout the second world war, for both the British and US intelligence agencies. At its height, Bletchley Park had a personnel roster over 10,000 strong, three quarters of which were women and the majority of which held degrees in mathematics, physics or engineering or held backgrounds in several European languages. Many of the personnel worked at Bletchley in secret, even to close family. It was signal intelligence on a previously unseen, industrial scale, filing over 4,00 messages daily and it paid huge dividends for the allied forces who cracked both the Enigma and Lorenz Ciphers at Bletchley, allowing the majority of coded, German communications to be read in plain English for the duration of the war, utilising the very first electronic computers ever to be engineered. Whilst Bletchley Park remains the most famous SIGINT operation of the Second World War, there were also hundreds of civilian amateur radio enthusiasts, named VI’s or voluntary Interceptors vetted and enlisted to listen in, write down and pass on coded signals to the military, some working up to 160 hours a week, tucked away in garden sheds and rear rooms, writing down coded messages sent by the Gestapo and the SS.

In 1945, Peacetime fell across Europe, but it was within the framework of a strange new world. Superpowers vied for supremacy. The veil of the cold war fell and Signal Intelligence was to play a crucial role, as countries embedded their undercover officers across the globe. Agencies needed a way to communicate with these officers and what better way than radio? Bases, such as Little Sai Won in Hong Kong, an offshoot from the British Y Service, were fully manned as listening stations as the Cold War saw the airwaves filled with gibbering morse clicks, robotic voices, stretched tones and very occasionally, the odd conversation among operators, caught in the background. This was so effective a means of communication, it’s still in use today. One of radios strongest attributes, however, the commonality of receivers in everyday homes, so too poses a conundrum for todays intelligence agencies. We can hear it too.

Numbers Stations

Today, these signals breach our airwaves on the AM radio band and can be heard almost 24 hours a day on one hour or another. In general, the broadcasts can be classified into three categories, numbers, morse and noise, though all three tend to fall into the collective umbrella term of what has been dubbed as “Numbers Stations”. These numbers stations send out curious broadcasts, many on tight, unflinching schedules, indeed, one can even find websites online ran by enthusiasts that maintain listings for each broadcast which reads like a twisted, entertainment guide, with names having been assigned to each station, often reflecting a certain characteristic of each particular broadcasts opening, such as the Lincolnshire Poacher, Bulgarian Betty or The Gongs Station..

Whilst each station is unique to a degree, all except a few outliers tend to follow a set structure. As the broadcast starts either on the half hour, or top of the hour, a header is played, this is to alert the listener that a broadcast is about to begin and consists of, in many cases, a musical tune or a grouping of rising and falling tones repeated several times over, such as the, the most famous examples probably being the Lincolnshire Poacher, or the Swedish Rhapsody..


In some cases, voice clips, as in the Yosemite Sam station can be heard.


After this short introduction, the message proper begins and a voice reels off groupings of numbers, often in a female, or child’s voice, often pre-recorded, mechanical or digitally rendered, though there are some which use men’s voices and others, more so historically, that utilised live readings


In the case of the morse or noise broadcasts, a message sent in morse code, or a tight grouping of tones are broadcast instead.


These messages can last, at times, for up to 45 minutes and are often themselves as uniform in structure as the broadcasts as a whole, the Lincolnshire Poacher, for example, sends blocks of 200 sets of numbers daily, though it’s highly likely that many of these broadcasts are dead messages, or messages filled with garbage, to help ensure that when a real message needs to be sent, it will not stand out and will further reduce the likelihood that specific activity would be uncovered.

Once the body of the message has completed, the broadcasts complete, either by repeating the initial header, or by simply repeating a sign-off word such as “END”.

Though very little is known about the actual history of the numbers stations as we hear them today, owing not in small part to their clandestine nature, it’s fair to presume that the stations we hear currently have not evolved in great leaps since the earliest broadcasts during the first world war, and almost certainly are very close to those used during the second world war. Indeed, along with the broadcasts themselves, even this story from Doctor Arthur Gee, one of the civilian radio amateur VI’s enlisted during the Second World War to listen to the broadcasts, also bears a striking resemblance to both the enthusiasts who tune in to document these numbers stations today as well as our current understanding of the broadcasts themselves.

“A chap came to see me one day, he was in civilian clothes but I formed the opinion he was probably from the Navy. He outlined the scheme to me, saying that if I could help he would be very pleased for me to do so. After he’d outlined the scheme, I thought “well, here goes, it’s certainly a good idea”, but if we do get invaded, I’ve more or less signed my death warrant no doubt. Anyway, we signed on the dotted line and started off. It was very very interesting, because we had to listen to certain frequencies on the radio that we were given and copy down the sort of code that we heard. I was always very intrigued to know just exactly what these signals were and who was listening to them, who we were listening to, what they all meant and so forth. I must say that even until this very day I’m not really quite sure exactly what we were listening to and what it all meant.”

One report forwarded to the MI5 from a VI shows random strings of five letters, not entirely dissimilar to the groupings we hear over numbers stations today.

As curious as they are, broadcast at all times of day, with such fixed regularity and in all manner of languages, do they actually mean anything? Surely after all these years, our governments have developed more modern techniques for distributing intelligence to overseas operatives? Do we still run spies, like those imagined in black and white movies filled with espionage and silent meetings in empty train stations and are those spies really hunched over a small household radio in their kitchens, scribbling down these coded messages and cross referencing them with their own code books, hidden in false drawers and under loose floorboards? How do we know these modern broadcasts are intended for clandestine intelligence networks and spies in the first place and are not just random broadcasts with little or no meaning, sent by other radio amateurs, mimicking age-old techniques?

Silent Receivers

For decades now, radio enthusiasts have tirelessly twiddled knobs, peering through the static to document and try to understand the exact purpose and meaning of the stations broadcasts. One of the earliest papers published on the subject, written by Simon Mason and titled “Secret Signals” was in 1991, and it listed pages upon pages of schedules and frequencies, itself a code to the uninitiated. In 1993, this prompted a group of radio enthusiasts calling themselves ENIGMA, The European Numbers Information Group And Monitoring Association. based in Yorkshire, England to form with an express interest in Numbers Stations. This group of shortwave radio operators worked together to form much of what is still known and mirrored today around the numbers stations. Nicknames were assigned to clear confusion when talking about various broadcasts and a system of classification was developed to specify a stations type and language, M for morse, S for Slavic languages, G for German, E for English, V for various and X for non-voiced stations. Much of the information was disseminated through newsletters and booklets. The very first newsletter published by Enigma in 1993 documented stations named “Two Letter German”, “Station NNN”, “Five Dashes”, “The Lincolnshire Poacher” and “Swedish Rhapsody”, with a brief description of each stations format and known radio frequency. By the time of the ENIGMA groups formation, enthusiasts had already been listening, and theorising, for many years what the stations might be and from the early 1970s’, the main theory, that they were messages operated by government secret service departments, intended for overseas spies, was long-running and universally agreed upon as the correct interpretation of their use.

In issue three of the ENIGMA newsletter, published in October of 1993, the following article on a station named the “Tyrolean Music Station” was featured and showed just how accepted the spy theory was at the time:

“Does anyone remember the Tyrolean Music & Numbers Station? This station operated in the 1970’s, it operated on Saturday and Sunday’s on 6425 and 6660 KHz and was almost certainly the most individual Numbers Station of them all.

Messages were addressed to named agents in German, and the transmitting site was probably on the French / Swiss border.

The typical Tyrolean format was of a 7 note orchestral, taken from the Communist Internationale, a German male then announces names of agents e.g. Heinrich, Fowler, Dover. Messages then follow for each agent separately.

Occasionally bizarre variations to this standard format e.g a ourth tune then added, non standard tunes played interspersed with cryptic messages read out by the same announcer, such as “Der Sonne Schein Vorlisch” (The sun shines gone out).

The station even sent out Christmas Greetings on 26th December, 1971.”

The theory that these stations were intended to be received by spies was not merely plucked from the air, however, for a long time it was based purely from speculation surrounding the sheer amount of resources it would have taken to run such a large radio operation. On top of this running cost, the actual broadcasting of such a station would be deemed as illegal, as none are listed or licensed to broadcast. Then there are the Jammers. Known as “Warblers”, many of the stations are jammed by another station broadcasting on the same frequency, using a higher powered signal. Frequently, number stations have been jammed with an oscillating tone in an attempt to knock the original broadcast off the air, or at the very least, to obfuscate the message enough to make it difficult to interpret. Who would be going to such lengths and expenditure if the stations were not so important? One often touted line from officials is that they are broadcasting innocuous weather information, a story that was also utilised by the BBC, when a listener from Anderra who had tuned into the World Service had her service interrupted by the Lincolnshire Poacher. The radio presenter read her letter on air and replied, telling her the numbers related to snowfall figures in her local area.

As for the actual content of the messages, interpreting it as code of some sort was theorised early on and attempts to crack the messages, or at least make sense of some of the recurring elements were made.

A very simple, but sound coding technique was initially theorised amongst enthusiasts, known as a book cipher. As the name implies, encryption and decryption of messages utilises a book to encode a message. The sender and recipient both own a copy of the same book, agreed upon in advance and then a message is sent using digits which determine the page number and the number of the word on the page itself, for example 115 23, on the 115th page of the 2006 Arrow Books publication of “To Kill a Mockingbird”, the 23rd word would be “room”. Provided you and me both own this same edition, a perfectly innocuous item, free of any suspicion, I could feasibly encode a message that only you would be able to understand, unless of course an outsider was to obtain the information on which book and which publication was to be used. Indeed, there are some numbers stations still running today that some people still believe to be using a form of book cipher.

More predominantly, however, is the assumption that the messages were being encoded using a “one time pad” Cipher. Much like the book cipher, one time pads are, like the numbers stations themselves, incredibly basic, however, impossible to understand unless one was the intended recipient. Despite their simplicity, their use of randomized elements makes them mathematically unbreakable by any form of brute force, or logic based decryption techniques, the only possible way to break a one time pad is to hold the key itself.

One Time Pads

A one time pad cipher works in many ways similar to the Book Cipher previously mentioned, however, rather than a published book, the code is encrypted and decrypted using a series of random blocks of numbers, this is what would be the “One time pad”, so called as each number in the block is used only once and then discarded.

Firstly, the letter and numbers to be used are assigned a random two digit number, in the most simple terms, A = 01, B = 02, C = 03 and so on. The person encrypting the message would then look at the first two digit number in their one time pad, for example, 40. They would then use simple addition to add 40 to the number assigned the letter they wish to encrypt, in this case, we will use the letter C with the assigned number of 03, giving us a total of 43. This two digit number is then sent to the recipient and the number 40 on the one time pad discarded.

The recipient then receives the number 43, references their one time pad, which is an exact copy of the senders, with the first number of 40, subtracts 40 from 43, leaving them with 03, looks up the reference key to see that 03 refers to the letter C and then they too discard this first number. This system is used over and over, discarding each two digit number on the pad in order as they are used, to spell out words until the message is complete.

Using incredibly simple mathematics that anyone could do quickly and without trouble, only needing a pencil and paper, a message could be encoded in this way that no computer could ever break. The pads themselves could be easily concealed if made small enough and could be printed on materials such as rice paper, that could either be burnt, or even eaten leaving no trace.

Playing with codes is all fun and games, however, how is this relevant to numbers stations and not just simple speculation or conspiracy theories on the part of the radio enthusiasts who were tuning in? Despite the prevalence and out-in-the-open nature of these broadcasts, not a single government had yet come out and admitted to running them. In fact, no government had yet even acknowledged their existence. In 1988, however, pieces of the puzzle began to fall in to place and the picture was exactly as the enthusiasts had expected.

Spooks among us

In 1988, 42 year old Dutch immigrant, Erwin Van Haarlem, was arrested in his North London apartment. He had moved to the United Kingdom in June, 1975 and worked as a waiter in the Hilton Hotel on Park Lane before opening an art dealership on Bond Street. As it turned out, Van Haarlem was not quite the art dealer he had been posing as, nor was he Dutch. In fact, he hadn’t ever been to the Netherlands in his life. Erwin Van Haarlems real name was Vaclav Jelinek, a Czech national, working for the Czech StB, a secret service that reported directly to the Soviet KGB and he had been sent to London to spy on the UK and the US.

Upon his arrest, magazines were found in his apartment packaged and addressed to Czechoslovakia, full of encoded messages as well as equipment for writing in invisible ink. There was also the recovery of a list of places that secret messages could be deposited and collected from, such as a broken wall in a pub named the “Minstrel Boy” along with a tree on the outskirts of a local golf course. As well as all this, six, tiny one time pads were found, three of which were hidden inside bars of soap and of course, a shortwave radio.

In court, it was heard that Jelink had received over 200 messages from a Morse Numbers Station transmitting from Prague, and they even read several of the messages he had received:

“Prepare your report for hand over in Vienna, repeat Vienna. Indicate how you use the microfile”. “Regarding immigration, use your initiative”. “Send only news about intended actions against the Czech Socialist Republic”

Jelinek was jailed and later released and deported back to the Czech Republic, but quite aside from that, Numbers Stations now had solid, documented evidence as to their usage and the argument for what the stations were was seemingly settled, moving one foot outside of the realms of the conspiracy theory.

With the fall of the Berlin wall in 1989 and the dissolution of the Soviet Union in 1991, many of the long-running numbers stations fell off the air, the Gongs station was a particular favourite, known for it’s off kilter, 8-note header, warbling in it’s spooky, haunting manner disappeared in May of 1990.


This sudden dropping off of activity was not considered to be a coincidence, however, it wasn’t until the late 90’s that any new information regarding the numbers stations would find its way to the public.

The first ever official confirmation came from an article published in 1998 by the British newspaper, The Daily Telegraph when they printed an article relating to numbers stations with the Headline “Counting Spies”. The article quoted a spokesperson for the Department of Trade, at the time the regulator for Radio in the UK as saying:

“These numbers stations are what you suppose they are. People shouldn’t be mystified by them. They are not for, shall we say, public consumption.”

Also in 1998, “The Cuban Five” Gerardo Hernández, Antonio Guerrero, Ramón Labañino, Fernando González, and René González, were arrested in Florida. They were part of a larger network of Cuban spies operating within the WASP network for the Cuban DGI, to spy on the US. They received directions from Cuba from the numbers station known as “Atencion”, a station that had been documented as early as 1962 and continues until today.


The same station also played a role in the case of Ana Bel Montes in 2001, a senior defense analyst working inside the Defense Intelligence Agency in the US as one of the foremost specialists on Cuba. She had in fact been spying on the US since 1985, sending information back to Havana and receiving messages via a Sony shortwave radio. Upon a search of her apartment and a forensic search of her laptop hard drive, many deleted messages were found relating to receiving messages via the “Atencion” station.

“Further analysis of MONTES’s copied Toshiba hard drive identified text consisting of a series of 150 5-number groups. The text begins, “30107 24624,” and continues until 150 such groups are listed. The FBI has determined that the precise same numbers, in the precise same order, were broadcast on February 6, 1999, at AM frequency 7887 kHz, by a woman speaking Spanish, who introduced the broadcast with the words “Attencion! Attencion!”


Similar stories involving the “Atencion” station in America include the arrest of Carlos Alvarez in 2006 along with Walter Kendall Myers and his wife Gwendolyn Steingraber Myers in 2009, all of which were arrested for spying on the US for Cuba and all of which heard readings in court referring directly to the same Cuban station.


First documented in the 1970s until it fell of the air in 1990, the station known as OLX was confirmed to have been run by the Czech Ministry of Information, when Numbers Station enthusiast, totoCZ emailed the Czech authorities to enquire on the off chance, of the station. The reply came as quite a shock, after years of government denial and refusal of acknowledgement.


it was shortwave radio, broadcasting into foreign countries, which was being conducted by the Office for Foreign Relations and Information, formerly of the Ministry of Information, the MoI.”

In what might be seen as a flurry of information after such a drought, documents were also published in the “Numbers and Oddities” Newsletter, in May of 2014, obtained through Polish archives. The documents were originally intended as part of a training manual for Intelligence service agents in how to interpret numbers stations sent from the station “Swedish Rhapsody”, well known for its musical header and strange, childlike voice pronouncing “Achtung!” before reeling off it’s numbered messages. Swedish Rhapsody was well known for its frequent straying across the Radio band, often freaking out unsuspecting listeners of the BBC World Service as it ghosted into their reception.


Among the various, significant details revealed in the document, was the interesting tidbit that after almost 40 years of being nicknamed “Swedish Rhapsody” after the stations musical piece in its header, the music was actually named “Luxembourg Polka”, played from a music box.

British intelligence agency GCHQ were the last to officially give any confirmation to the numbers stations. When asked of their operation, they replied simply:

“GCHQ are aware of the existence of numbers stations but cannot comment on operational matters.”


Through tireless efforts of the enthusiasts, as well as individual cases of ex-intelligence operatives telling their stories, small secrets of the bizarre broadcasts have slowly been extracted, we know now for example that The Gongs Station was a Stasi run station, transmitting from Wilmersdorf, just outside of Berlin and that the Lincolnshire Poacher is run by the British and transmits from an RAF base in Cyprus. There are many stations however, that still hold tight their mysteries. Some pop up and then disappear for several years, even decades before reappearing, some disappear forever, whilst others, seemingly transmit in clicks and beeps without ever ending. The Buzzer is one such station.


The Buzzer broadcasts from various sites inside Russia and was documented as early as 1976. For over thirty years it ran a continuous broadcast consisting of an intermittent buzzing tone. Theories on it’s purpose ranged from the simple, that it was a placeholder keeping a radio channel open, to the more out there, that it was either a kind of dead man’s switch, or part of the Soviet Dead Hand, an automated nuclear launch system used as part of a mutually assured destruction plan.

That was, until in 2010 when after nearly thirty years the Buzzer suddenly changed and the tone used rose, and then again lowered. The buzzer continues today and though messages are now broadcast at times on the frequency, no one has any explanations as to why Russia would broadcast a single, beeping tone for what is now approaching fifty years at a not insignificant cost.

The Russian Woodpecker too, hopped around the frequency band for a decade between the years of 1976 and 1986, broadcasting a repetitive knocking sound. Broadcast from Chernobyl, it was so powerful a signal that it routinely knocked legitimate broadcast stations off the air , interrupting transmissions with its peculiar rattling.

After the fall of the Berlin wall in 1989 and the break up of the USSR in 1991, numbers stations in Europe diminished greatly, with some stations falling off the air completely, though activity remains strong in Europe and in the USA, many broadcasts, such as the Voce De La Chica, originating from Cuba, continue unabated. As well as these long-running Stalwarts, many new stations continue to appear, often originating from the Far-East, the New Star Broadcasting station from Taiwan


Which opens with traditional Eastern flute music, leads on to an overly enthusiastic announcer who calls out messages such as “Please get ready to receive your message!” and Radio Pyongyang from North Korea, which fell of the air for over 15 years only to suddenly reappear in 2016 are two such examples.

There are still many other stations broadcasting right now, probably some whilst you have been listening to this podcast. But why would a modern sophisticated government still be using technology that dates back almost one hundred years? The simple answer is that they are effective. Shortwave radio travels significant distances, as the signal bounces off the atmosphere and back again off the surface of the earth, it can pinball around the globe in this way for thousands of miles. They are secure in this modern age when satellites, phones, email and internet usage can all be hacked, tracked, traced and filed.. All an operative needs in the field is a simple radio, bought from any high street to tune in and receive a transmission. Bruce Schneir, a security Analyst said of the stations:

“You can’t identify who the recipient is, or where they might be. The recipient might be anywhere in one third of the planet. As a covert channel, it works very well.”

Whilst some stations transmit random blocks of numbers, their headers having now been interpreted to inform a recipient of exactly how many blocks are to be sent in any given message, other stations transmit set blocks of numbers, such as the Lincolnshire Poacher which always transmits 200 blocks of numbers in every message, in order to conceal messages within another layer of security, so that even those who cannot understand the content cannot also determine if a real massage is being sent or if activity is lessening or heightening at any particular time.

Others have speculated that many stations, including both New Star Broadcasting from taiwan and Radio Pyongyang from korea, are broadcasting nothing but garbage and are used as a form of psychological warfare, to make others believe that they are operating spies in foreign territories, after all, it is far cheaper to operate a numbers station than it is to operate an actual underground spy network.

As numbers stations continue to broadcast, so do they continue to fascinate those who dig through the static, retrieving messages they will never understand. Unlisted, unlicensed and with no one admitting to using them, like any good mystery, the allure of a secret, hidden in plain sight creates an information vacuum that allows our imaginations to ignite. Who is listening and what are they saying? Achtung! 1, 2, 3, 4, 5…..

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