Major thirds tuning in English, a convention that is followed in this article. While standard tuning is irregular, mixing four fourths and one major third, M3 tunings are regular: Only major-third intervals occur between the successive strings of the M3 tunings, for example, the open augmented C tuning For each M3 tuning, the open strings form an augmented triad in two octaves. For guitars with six strings, every major-third tuning repeats its three open-notes in two octaves, so providing many options for fingering chords. By repeating open-string notes and by having uniform intervals between strings, major-thirds tuning simplifies learning by beginners. These features
Major thirds tuning of major-third and minor-sixth intervals are termed "inverse intervals" in the theory of music. Consequently, chord charts for minor-sixths tunings may be used for left-handed major-thirds tunings; conversely, chord charts for major-thirds tunings may be used for left-handed minor-sixths tunings. Major-thirds tuning facilitates playing chords with closed voicings. In contrast, standard tuning would require more hand-stretching to play closed-voice seventh chords, and so standard tuning uses open voicings for many four-note chords, for example of dominant seventh chords. By definition, a "dominant seventh" is a four-note chord combining a major chord and a minor seventh. For example, the C7 seventh