2668: International Telecommunication Union (ITU) Standard Apr 7, 2022

Morse code was changed a number of times, finally cemented in 1865 with the International Telecommunication Union standard. This was mostly based on Morse's original system, as well as Gerke's modified European version, but some letters were redesigned wholesale like those for <O> (once • • with a medial pause, to later – – –) and <P> (once • • • • •, later • – – •). It also distinguished <I> and <J> that Gerke's system had as the same (• • without the medial pause), though it does not use Morse's original <J> (– • – •) because this was instead used for <C>.

This left only 4 characters unchanged since the original system. Per letter this did actually make things longer to spell & therefore become on the surface less efficient, but it led to a greater ease of understanding that would cancel that out. It has little resemblance to the original Morse code, but many still call it as such, even though the technical name would be the International Telecommunication Union (ITU) standard.