AR (End of Message) in Morse Code

Dot-dash-dot-dash-dot: ·—·—· . Like SOS, AR isn't sent as five separate letters — it's a single unbroken prosign, run together with none of the normal gaps between characters, which is exactly what tells a receiving operator to read it as a procedural signal rather than spelling out anything.

"End of Message," Specifically — Not "End of Contact"

AR marks the end of a single message or transmission, signaling that the sender has finished what they were saying but the overall exchange between the two stations isn't necessarily over yet — more traffic, a reply, or further messages might still follow. That's a meaningfully different signal from SK, which specifically marks the end of an entire contact between two stations. Mixing the two up in formal traffic can genuinely confuse a receiving operator about whether to expect anything more, which is why the distinction between them has stayed a standing part of Morse operating procedure rather than fading into interchangeable use.

Where AR Shows Up in Practice

AR commonly appears at the close of formal written traffic — a completed telegram-style message, a net control announcement, or the end of one exchange within a longer contest or ragchew — often followed immediately by a separate prosign like K inviting the other station to transmit next. Amateur radio operators still use AR today in exactly this procedural role during CW contacts, which makes it one of the small handful of prosigns that never really left active daily use even after Morse code's commercial and maritime applications wound down.

Why It's Sent as One Unbroken Signal

Running AR together without letter gaps serves the same functional purpose it serves in SOS: it makes the signal unmistakably a procedural marker rather than an attempt to spell the word "AR," and it stays recognizable even through a weak or noisy connection where individually spaced letters might blur together or get misread as something else entirely.