Custom divisions of the octave

You can change the number of divisions of the octave for an existing tonality system, or create a new tonality system with as many divisions of the octave as you like.

In the Divisions section of the Edit Tonality System dialog, you can change the number of divisions assigned to each interval. The total number of divisions of an octave, which is shown at the top of the section, is updated automatically as you change the number of divisions.

In Equal temperament, or 12-EDO, the total number of divisions is 12. There are 2 divisions between A and B, 1 division between B and C, and so on. This follows the standard Western pattern which you can also see in the pattern of white and black keys on a keyboard.

Although you can divide the octave into any number of divisions, the number of equal divisions in the octave must be divisible by 12 to be able to show a standard Western key signature in Dorico Pro.