Many of the smaller floor frames (like Jasmine) do not have cross braces. Does it wobble from side to side? Your cat seemed pretty confident up there. I think maybe the slot on the legs is so you can raise and lower the height of the quilt surface, the adjustment of the length of the back leg would change the working angle and the hole on the other leg might just be for a peg to lock the spread of the feet. Don't know for sure and I was unable to find a similar looking one on the web. Sorry.