Lowest note name, without octave.
Chord symbol, with a slash bass when the lowest note is not the root: 'C7', 'C7/E'.
Formula members that do not sound ('5'; '9' and '11' in eleventh and thirteenth chords).
Key of the formula in CHORD_FORMULAS ('M', '7', 'maj9'…).
Root note name, without octave.
The lowest note is the root.
1 for a complete chord over its root; less for each omitted member, another bass, and each tension.
Members above the octave: '9', '#11', 'b13'…
One reading of a set of notes as a chord, with what ranks it (see
Harmony.detectChordsScored).