[Edit] Because this variant lacks promotion choice, but makes the promotion piece dependent on location, the standard promotion procedure was suppressed by defining maxPromote=0 (i.e. no promoting pieces). A JavaScript function WeirdPromotion was then defined in the HTML, in addition to the diagram description. The diagram standard script calls this function when present, to tell it what piece type to put on the to-square.
The provided function tests if the moved piece was a Pawn that reached last rank. If so, it specifies a piece type dependent on the promotion file.
Because the true rules differ so much from what is described above, I figured the article deserves to have an extra diagram with piece moves:
Click on names below to see how the piece moves.
[Edit] Because this variant lacks promotion choice, but makes the promotion piece dependent on location, the standard promotion procedure was suppressed by defining maxPromote=0 (i.e. no promoting pieces). A JavaScript function WeirdPromotion was then defined in the HTML, in addition to the diagram description. The diagram standard script calls this function when present, to tell it what piece type to put on the to-square.
The provided function tests if the moved piece was a Pawn that reached last rank. If so, it specifies a piece type dependent on the promotion file.