six-string guitars, the M3 tuning: F2–A2–D3–F3–A3–D4 loses the two lowest semitones on the low-E string and the two highest semitones from the high-E string in standard tuning; it can use string sets for standard tuning. Note that regardless of which note is chosen to start the tuning sequence, there are only four distinct sets of open-note pitch classes. The major-thirds tunings respectively have the open notes : {E, G#, C}, {F, A, C#}, {F#, A#, D}, and {G, B, D#} Properties Major-thirds tunings require less hand-stretching than other tunings, because each M3 tuning packs the octave's twelve notes into four consecutive frets. The major-third intervals allow major chords and minor chords to be played with two–three consecutive fingers on two consecutive frets. Every major-thirds tuning is regular and repetitive, two properties that facilitate learning by beginners and improvisation by advanced guitarists. Four frets for the four fingers In major-thirds tuning, the chromatic scale is arranged on three consecutive strings in four consecutive frets. This four-fret arrangement facilitates the left-hand technique for classical (Spanish) guitar: For each hand position of four frets, the hand is stationary and the fingers move, each finger being responsible for one fret. Consequently, three hand-positions (covering frets 1–4, 5–8, and 9–12) partition the fingerboard of classical guitar, which has exactly 12 frets. Only two or three frets are needed for the guitar chords—major, minor, and dominant sevenths—which are emphasized in introductions to guitar-playing and to the fundamentals of music. Each major and minor chord can be played on two successive frets on three successive strings, and therefore each needs only two fingers. Other chords—seconds, fourths, sevenths, and ninths—are played on only three successive frets. For fundamental-chord fingerings, major-thirds tuning's simplicity and consistency are not shared by standard tuning, whose seventh-chord fingering is discussed at the end of this section. Repetition Each major-thirds tuning repeats its open-notes after every two strings, which results in two copies of the three open-strings' notes, each in a different octave. This repetition again simplifies the learning of chords and improvisation. This advantage is not shared by two popular regular-tunings, all-fourths and all-fifths tuning. Chord inversion is especially simple in major-thirds tuning. Chords are inverted simply by raising one or two notes three strings. The raised notes are played with the same finger as the original notes. Thus, major and minor chords are played on two frets in M3 tuning even when