The top gets the female dots.
The iron get the males.
Without the curtains, these are connected.
The corner curtain gets hermaphrodite/hybrid ones that are female on the underside for snapping onto the irons but without the typical round button backing (having trouble finding a pic). The backing is a male. This hybrid fastener makes the curtain a middle layer. The top will attach to the male side of the curtain when it is installed between the iron and the top.
The curtain goes on the irons, the top snaps onto the curtain. So in layers, it's irons, curtain, then top. At least that's the way ours is configured today.
If you can imaging removing the screw threads and putting the two pictures together that's the fastener. It has the two sides shown in my third picture.
