Scales in the music library are defined as pitch class sets (i.e., chromatic scale degrees within one octave). Scale values range between 0 and 11. The first pitch is often 0, denoting the starting (root) note.

Here are some predefined scales:

AEOLIAN_SCALE = [0, 2, 3, 5, 7, 8, 10]
BLUES_SCALE = [0, 2, 3, 4, 5, 7, 9, 10, 11]
CHROMATIC_SCALE = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
DIATONIC_MINOR_SCALE = [0, 2, 3, 5, 7, 8, 10]
DORIAN_SCALE = [0, 2, 3, 5, 7, 9, 10]
HARMONIC_MINOR_SCALE = [0, 2, 3, 5, 7, 8, 11]
LYDIAN_SCALE = [0, 2, 4, 6, 7, 9, 11]
MAJOR_SCALE = [0, 2, 4, 5, 7, 9, 11]
MELODIC_MINOR_SCALE = [0, 2, 3, 5, 7, 8, 9, 10, 11]
MINOR_SCALE = [0, 2, 3, 5, 7, 8, 10]
MIXOLYDIAN_SCALE = [0, 2, 4, 5, 7, 9, 10]
NATURAL_MINOR_SCALE = [0, 2, 3, 5, 7, 8, 10]
PENTATONIC_SCALE = [0, 2, 4, 7, 9]

You can define your own scales in a similar way. For instance,

MY_SCALE = [0, 1, 4, 7, 11]

Again, scale values may range between 0 and 11.

However, it is also possible to define microtonal scales. This is a more advanced topic (see section on microtonal music).