Most accordionists today use lead sheets. But some of us old-timers remember AAA, which makes learning Stradella bass easy. Treb le staff is the same as piano. Bass staff has the following changes:
1. Notes below third line or on third line with stems going up are single bass notes.
2. Notes above third line or on third line with stems going down are chords, with symbol M (major), m (minor), 7(dominant seventh), or d (diminished seventh) in space between staves to indicate the type of chord.
3. Underscore below bass staff indicates bass note to be played in counterbass column.
4. Liberal use of fingering notation where necessary.