Listen to a real Morse contact and you will hear patterns that are not letters, numbers or punctuation. They arrive at the start and end of transmissions, and between sections of a message. These are prosigns — procedural signals — and they are the punctuation and traffic control of Morse operation.
What makes a prosign different
A prosign is two or more letters sent run together with no gap between them. Normally there is a three-unit gap between letters. In a prosign that gap is removed, so the letters fuse into one longer character with its own distinct rhythm.
Take AR. On its own, A is .- and R is .-.. Sent as a prosign they become .-.-. — a single five-element character. To an experienced ear it does not sound like "A then R"; it sounds like one thing that means "end of message."
Because they are written as separate letters but sent as one, prosigns are conventionally shown with an overbar across the letters. In plain text where an overbar is not available, they are usually written inside angle brackets: <AR>, <SK>, <BT>.
The key point: if you leave a normal letter gap, you have sent two letters. If you close the gap, you have sent a prosign. The individual dots and dashes are identical — the spacing carries the entire meaning.
The prosigns you will actually hear
AR — end of message
.-.-. — Marks the end of the message you are sending. It does not end the contact; it says "that is the end of this transmission." Often sent right before you hand over to the other station.
SK — end of contact
...-.- — The conversation is over. Sent at the close of a QSO, usually after final courtesies. Also written VA, because the same sequence of elements can be split either way — it is the identical sound regardless of which letters you use to name it.
BT — break / new section
-...- — A separator inside a message, equivalent to a paragraph break or a dash in written text. You will hear it constantly in longer transmissions, dividing one idea from the next. It is also the double-dash punctuation mark in standard Morse.
KN — go ahead, specific station only
-.--. — "Over — but only to the station I am working." Used when you want the station you are already in contact with to reply, and are asking everyone else to stay off. Useful in a crowded band.
K — go ahead, anyone
-.- — Just the letter K, but used procedurally. It invites any station to reply. This is what you send at the end of a CQ call.
AS — wait
.-... — "Stand by, do not go away." Sent when you need a short pause — someone at the door, a pen to find. It tells the other operator that the contact is still live.
CT or KA — attention, starting signal
-.-.- — Sent before the start of a transmission to signal that a message is beginning. Think of it as clearing your throat before speaking.
The error sign — eight dots
........ — Eight dots in a row means "disregard the last word, I am about to send it again." It is the standard correction signal and part of ITU-R M.1677-1. If you hear a run of dots that seems far too long to be H, this is what it is.
SOS — distress
...---... — The most famous prosign of all, and a perfect example of why the spacing matters. SOS is sent as one continuous character with no letter gaps. Sent with gaps it is simply the letters S, O and S; sent run together it is the international distress signal. Read the full story in SOS in Morse code.
How prosigns fit into a real contact
A simple exchange, with prosigns doing the structural work:
- CQ CQ CQ DE [callsign] K — calling anyone, then K to invite a reply.
- [their call] DE [your call] BT — addressing them, then BT to move into the body.
- Signal report, name, location… BT between sections.
- AR [their call] DE [your call] KN — end of message, handing back specifically to them.
- …and at the very end, SK.
Once you can hear these, transmissions stop being an undifferentiated stream and acquire visible structure — you know where a message starts, where it breaks and where it ends, even if you miss words in between. That alone makes copying real traffic dramatically easier.
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Prosigns are not abbreviations
It is easy to confuse prosigns with the shorthand operators use, but they are different things:
- Prosigns are single fused characters that control the transmission — AR, SK, BT.
- Abbreviations are ordinary words sent as separate letters — 73 (best regards), FB (fine business), GM (good morning).
- Q codes are three-letter groups with fixed meanings — QTH (location), QRS (send slower), QRZ (who is calling me).
All three appear constantly in the same transmission, but only prosigns break the letter-gap rule. The abbreviations and Q codes page covers the other two categories in full.
Learning them
Prosigns are easier than they look, because there are only about eight in regular use and each has a distinctive rhythm. The trick is to learn them as sounds, exactly like letters — not as "A plus R." If you think of AR as two letters you will keep hearing two letters.
Use the translator to play them and listen for the shape. Then look for them in real recordings: once you can pick out BT and AR, the structure of a transmission becomes obvious even when the words do not.
For everything else in the standard — the full punctuation set including the @ sign added in 2004 — see Morse code punctuation and the complete Morse code chart.