The All Fourths Tuning, also known as the P4 Tuning, is a regular tuning which has a measure of popularity among electric guitar players in particular.
The P4 ‘All Fourths’ Tuning is a regular tuning, which means the intervals between the paired notes of their successive open strings are equal. By consequence, there is perfect pattern regularity on the guitar fretboard. This eliminates the necessity for alternative systems like the CAGED System, which belongs to the domain of the Standard Tuning.
Players associated with the P4 Tuning
Jazz-Rock patriarch Allan Holdsworth is also known to having made extensive use of this tuning, particularly in his SynthAxe days when he could switch tunings at the press of a button.