Zahn
A tricky task. How to tie the middle of a rope to a fixed ring. There are no ends of the rope to use, and no “ends” of the item you are tying to.
Put the middle of the rope through the ring.
Pull the middle of the rope down, making a bunny ear. Center it between the left and right sides of the rope.
Wrap the bunny ear around one side of the rope making a hitch around it.
Yank down sharply on the bunny ear. The rope will flip over on itself. The bunny ear is now straight and the side rope will be hitched around it. If there is tension on the side rope, you may have to lift up on it in order for the hitch to flip over on itself.
Do the same thing on the other side. Slide the hitch from the last step up next to the ring and out of the way. Then wrap the bunny ear around the side rope making a hitch.
Yank down sharply on the bunny ear. Once again, the rope will flip over on itself, transferring the hitch from the bunny ear to the side rope.
Slide the second hitch up snuggly against the first. Wrap the bunny ear around the rope on the same side that you started with.
Yank down sharply on the bunny ear. It goes against common sense, but this third hitch actually is necessary to keep the knot all together.
In the finished knot, either of the side ropes will be able to hold tension on its own without the knot coming undone. Bring the two sides together and put weight on them both as a pair, and it will still hold tension without coming undone.