Prosigns for Morse code

Morse O), they all encoded more common characters into shorter keying sequences, and the rare ones into longer, thus effecting online data compression.

They were not defined by the developers of Morse code, but were gradually introduced by telegraph operators to improve the speed and accuracy of high-volume message handling, especially those sent over that era's problematic long distance communication channels, such as transoceanic cables and later longwave wireless telegraphy.

Among other prosign uses, improvement in the legibility of written messages sent by telegraph (telegrams) using white space formatting was supported by the procedural symbols.

To become an efficient telegraph operator it was important to master the Morse code prosigns, as well as the many standard abbreviations used to facilitate checking and re-sending sections of text.

[4] The only difference between what is transmitted for the Morse code prosign vs. the separate letter signs is the presence or absence of an inter-letter space between the two "dit" / "dah" sequences.

For example, when embedded in text the Morse code sequence  ▄▄▄ ▄ ▄ ▄ ▄▄▄  represents the "double hyphen" character (normally "=", but also "– –").

All are strictly used as normal strings of one to several letters, never as digraph symbols, and have standard meanings used for the management of sending and receiving messages.

(in-tur-ko) For the special purpose of exchanging ARRL Radiograms during National Traffic System nets, the following prosigns and signals can be used, most of which are an exact match with ITU-R and Combined Communications Electronics Board (military) standards; a few have no equivalent in any other definition of Morse code procedure signals or abbreviations.