Thanks Hugh, that's it.
I followed your link. And that doesn't really explain it. But the downloadable manuals do. It definitely is the left hand side of the accordion, and on the photos you can see that the later versions (lower two pictures) have the right arrangement of the left hand keyboard, also 45 degrees arrangement, like right hand and like the accordion. I like that.
I, personally, would have arranged it more like a piano keyboard. One line through, 6 rows. Left part switchable to accords like in the accordion. But if it is played in the melody bass arrangement, how melody in left hand is called in the accordion world, it would be more like a piano with chromatic keyboard than an accordion with melody bass. Why copy the disadvantage of the naturally split keyboard from the accordion to an organ?
In accordions melody bass can have different arrangements, only melody, melody still with the two bass rows, and an arrangement where accords and melody keys are present, which makes the left hand side big. So my preferred one would be 6 rows of only melody, so the keyboard would be one from lowest basses to highest tunes, but still left hand switchable to accords. Why not? It's all electronic and just doable by computer codes.
But thanks for the link. I certainly will keep an eye on this one,
Severin