Among alternative tunings for guitar, a major-thirds tuning is a regular tuning in which each interval between successive open strings is a major third ("M3" in musical abbreviation). Other names for major-thirds tuning include major-third tuning, M3 tuning, all-thirds tuning, and augmented tuning. By definition, a major-third interval separates two notes that differ by exactly four semitones (one-third of the twelve-note octave). The Spanish guitar's tuning mixes four perfect fourths (five semitones) and one major-third, the latter occurring between the G and B strings: E–A–D–G–B–E. This tuning, which is used for acoustic and electric guitars, is called "standard" 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. G–C–E–G–C–E. 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 also facilitate advanced guitarists' improvisation, precisely the aim of jazz guitarist Ralph Patt when he began popularizing major-thirds tuning between 1963 and 1964. Avoiding standard tuning's irregular intervals In standard tuning, the successive open-strings mix two types of intervals, four perfect-fourths and the major third between the G and B strings: E2–A2–D3–G3–B3–E4. Only major thirds occur as open-string intervals for major-thirds tuning, which is also called "major-third tuning", "all-thirds tuning", and "M3 tuning". The most viable M3 tunings are: E2-G#2-C3-E3-G#3-C4 F2-A2-C#3-F3-A3-C#4 F#2-A#2-D3-F#3-A#3-D4 G2-B2-D#3-G3-B3-D#4 G#2-C3-E3-G#3-C4-E4 All of these tunings reduce the overall range of the instrument a bit: the first takes a M3 off the top of the range, and the last takes a M3 off the bottom of the range. One popular M3 tuning has the open strings: G2–C3–E3–G3–C4–E4, which some guitarists have applied to the top six strings of a seven string guitar, with the low seventh string tuned to the low E, to restore the standard E–E range. While M3 tuning can use standard sets of guitar strings, specialized string gauges have been recommended. The middle tunings are a compromise, each losing a note or two off both the top and the bottom of the range. For example, for