> There are three in general use: AR signifies the end of the message, KN marks the end of your transmission and an invitation to the other station to reply, and SK says it’s the end of the contact and your last transmission to that station
> TLDR: We can thus conclude that the Morse code can be understood, and easily analyzed, as the composition of a prefix binary encoding of a 3 symbols alphabet {dot, dash, sep} into a binary alphabet, and a prefix encoding of a 58 symbol alphabet (57 characters and one space) into the 3 letters alphabet.
> The composition itself is a prefix encoding of the 58 symbols into a binary representation.
Check this part:
> However, some people would be inclined to recognize the space DET at level 2, thus making the alphabet quaternary, then using it directly at level 3, encoded as itself in level 2.
> This would meet the standard definition, for DET encoded in binary as 0000. But it would prevent the analysis of the binary encoding C2→1 as a prefix code, making it harder to show that CMorse is a prefix code, hence unambiguous.
In your link, AR, KN and SK can be considered in a similar way, but applied to the decoded message.
From http://lidscw.org/resources/cq-qso-template
> There are three in general use: AR signifies the end of the message, KN marks the end of your transmission and an invitation to the other station to reply, and SK says it’s the end of the contact and your last transmission to that station
See this nice discussion on the nature of morse:
https://cs.stackexchange.com/questions/39920/is-morse-code-b...
> TLDR: We can thus conclude that the Morse code can be understood, and easily analyzed, as the composition of a prefix binary encoding of a 3 symbols alphabet {dot, dash, sep} into a binary alphabet, and a prefix encoding of a 58 symbol alphabet (57 characters and one space) into the 3 letters alphabet.
> The composition itself is a prefix encoding of the 58 symbols into a binary representation.
Check this part:
> However, some people would be inclined to recognize the space DET at level 2, thus making the alphabet quaternary, then using it directly at level 3, encoded as itself in level 2.
> This would meet the standard definition, for DET encoded in binary as 0000. But it would prevent the analysis of the binary encoding C2→1 as a prefix code, making it harder to show that CMorse is a prefix code, hence unambiguous.
In your link, AR, KN and SK can be considered in a similar way, but applied to the decoded message.