Interpretation

Beware : this page may contain weird thinking.

For each phrase, each chord, and each scale, you will have the following objects. That’s every object that will be listed in dictionaries so developing the dictionary an abstraction further could really clean up the code. Ex: the GetID() function will belong all three objets.
We’ll have to think how to implement that but an inheritance of a commun father may solve that. Is it possible to do multiple inheritance in Django ? See Model Inheritance

The ID

For a chord

For the chord, the ID is the circle.

For a scale

For the scale, the ID is the circle.

For a phrase

For the phrase, the ID is the sorted set of circles.

The Readings

For a chord

For the chord, the reading is the name of the chord.

For a scale

For the scale, the reading is the name of the scale.

For a phrase

For the phrase, the reading is the sorted names of chords AND the sorted names of scales.

The instrument(s) representation(s)

For a chord

For the chord, the instrument representations are the voicings.

For a scale

For the scale, the instrument representation may be the whole neck of the guitar, of maybe a octave of the piano.
Not sure we will be implemented that but that would be a grreat feature, and i think it’s within the scope.

For a phrase

For the phrase, the instruments representations are the sorted set of voicings of each instrument.