Chord qualities and slash chords

The number is the root, counted up the major scale of the key, as in Reading a chart. Everything after it says what kind of chord it is, and nothing after it means a plain major triad.

That holds even where the scale would have made it minor. In a major key the 2, 3 and 6 chords are minor, but the chart still has to say so: a bare 3 is a major chord on the third degree, E major in C, and a session player will play exactly that.

• m — minor. It sits on the line with the number; every other quality mark rides above it as a superscript.
• ° — diminished: a minor triad with the fifth lowered.
• + — augmented: a major triad with the fifth raised.
• sus4 and sus2 — suspended: the third replaced by the fourth or the second.

Some charts write sus with no number. It means sus4 nearly every time, but the editor lets you write it bare, because a chart copied from paper should say what the paper said.

A 7 after the number is a dominant seventh, the flat seventh, on every degree and not only the 5. 37 is a major triad on the 3 with a flat seventh, E7 in C, the chord that pulls toward the 6m in a minor-key song.

The major seventh has to be written, because a bare 7 never means it: 4Maj7. On a minor chord the 7 is the minor seventh and is written as a plain 7 too, 6m7, because the m already said the third was minor.

Diminished chords come with two sevenths. °7 is the fully diminished seventh, every interval a minor third, nearly always a passing chord from outside the key.

ø7 is half-diminished: a diminished triad with a minor seventh on top, the chord the scale hands you on the 7. Some charts write it out as m7♭5, the same chord spelled by its parts.

A chord from outside the key takes a sharp or a flat before the number. The accidental belongs to the root, and the quality follows as usual: ♭7 with nothing after it is a major chord on the flattened seventh degree, B♭ in C, borrowed from the parallel minor.

♯4°7 is the passing diminished that walks the bass from the 4 up to the 5; it is the second bar of the example just above. Why ♭3 is always the minor third, in every key, is the minor-key songs lesson.

Ninths, elevenths and thirteenths stack on top of a seventh chord, and the highest number stands for the stack: a nine chord is a seventh chord with the ninth added, and the 9 takes the 7’s place, so it is 2m9 and not 2m7add9.

A 2 or a 4 added to a plain triad is written add2 or add4. The word is there because a 1 with a 2 after it looks like twelve. An add2 is not a sus2. The sus replaces the third and the add keeps it, which is why the first and last bars below, both built on the 1, are different chords. Only the 2 and the 4 take the word. A 6, 9, 11 or 13 prints bare, because a number on its own is what a chart writes for those chords. The editor’s Extensions sheet offers all six.

alt is the altered dominant, a 7 chord in which the player alters the upper notes at will: ♭9, ♯9, ♯11, ♭13. The chart is deliberately not saying which: a specific alteration like 7♭9 names one note, and alt names none. Written 7alt or simply alt, it is the same chord, and NNScharts keeps whichever you wrote.

A slash chord is a chord over a bass note that is not its root. The number on top is the chord and the number underneath is the degree in the bass: 1/3 is the 1 chord with the 3 in the bass, C/E in C. The bass is a degree like any other. It transposes with the rest, and it can carry an accidental: 1/♭7.

The mark speaks to the bass player and to anyone voicing the chord low: a bass stepping under a held chord, or a pedal tone. 4/1 is the 4 chord with the tonic held underneath. The chord is still the 4; only its bottom has moved.