[1] The conventional "standard tuning" consists of perfect fourths and a single major third between the g and b strings: All-fifths tuning has the set of open strings which have intervals of 3 octaves minus a half-step between the lowest and highest string.
The conventional tuning has an interval of 2 octaves between lowest and highest string.
It was used by jazz guitarist Carl Kress in the form All-fifths tuning has been approximated with tunings that avoid the high b' replacing it with a g' in the New Standard Tuning of King Crimson's Robert Fripp, which has been taught in Guitar Craft courses.
This new tuning is like a mirror to all kinds of string instruments including guitar.
All-fifths tuning is based on the perfect fifth (the interval with seven semitones), and all-fourths tuning is based on the perfect fourth (five semitones).