The best embodiment of Atzarin has intervals on the diagonals ascending from the row closest to the bellows to the row furthest from the bellows or closest to the hand rail in the case of bandonions and concertinas, and the note produced at any button whilst opening the bellows is a semitone higher than the note obtained at the same button whilst closing the bellows.
This produces an arrangement that is most familiar to players of other bisonoric arrangements and enables the most ergonomic, comfortable fingering and chord shapes.