International Telecommunication Union
Recommendation ITU-R M.1677-1: International Morse code is the primary source for the character set, procedural signs, spacing, and transmission framework used by the site. The ITU lists the 2009 revision as in force.
Library of Congress
The Samuel F. B. Morse Papers, the Library's Invention of the Telegraph essay, and the record for the first telegraph message of May 24, 1844 support dates, documents, and context surrounding early American telegraphy.
Smithsonian Institution
The National Museum of American History record for the Morse canvas-stretcher telegraph receiver and the Smithsonian's Vail Telegraph Collection provide material and archival context for Samuel Morse, Alfred Vail, telegraph instruments, and early operating practice.
How sources are used
Technical standards determine mappings and timing. Archival collections support historical statements. Practical listening guidance may draw on established operating conventions, but it does not override the international recommendation. A link records the source used; it does not imply endorsement of MorseCode.wiki.
Corrections and source suggestions
If a page conflicts with a primary source, send the page URL, the disputed statement, and the source through Contact and corrections. The team reviews the source before changing shared technical data or historical copy.