How to create "Reference Bindings" in Interface Builder?

I had some sample code I was working on and broke the link to a Reference Bindings and can't find how to get it back. The docs are not helpful at all and google is not return anything useful. The original looked like this http://mp.polymicro.开发者_如何学运维net/pastebin/20100821-CaptureIt-Picture-1.png

Discovered the problem, I could not see the forest for the trees.

If you break the link, it has to be reestablished by specifying the binding in the Bindings Inspector, Once you specify the binding it shows up in the connections inspector properly.