Encoding Rules
Each supported character has a stable sequence of short and long elements. E is one dot, T is one dash, A is dot-dash, and N is dash-dot. Numerals use five elements, producing a regular progression from 1 through 0.
Letter case does not change a Morse pattern. Unsupported characters should be reported or preserved clearly rather than assigned an invented signal. American Morse is historically related, but its mappings and timing differ from the international system.
The pattern is independent of its medium. It may be keyed as a radio tone, lamp flash, electrical pulse, tap, vibration, or printed mark as long as the timing remains distinguishable.
Timing Rules
A dot lasts one timing unit and a dash lasts three. Speed changes the duration of the underlying unit, not the ratio between marks.
In audio transmission, frequency controls pitch but not meaning. A higher or lower tone may be easier for a particular listener, while the encoded information remains in the sequence and duration of the keyed signal.
Spacing Rules
Elements within one character are separated by one unit of silence. Complete characters are separated by three units, and words by seven.
These boundaries are part of the code. In a recording or image, uncertain spacing can alter the inferred characters even when the individual dots and dashes are clear.
Prosigns
Prosigns are operating signals formed from combinations sent as one continuous character-like rhythm. AR marks the end of a message, SK the end of contact, and BT acts as a separator.
A prosign should be distinguished from the same letters sent separately. Its meaning comes from operating convention and continuous timing rather than ordinary spelling.
Sources and further reading
- International Telecommunication Union, Recommendation ITU-R M.1677, International Morse code.
- MorseCode.wiki Methodology and Sources & Standards.
- Institutional telecommunication and radio operating references cited in the source record.