What is the point info out of a Shared Site

I am trying to understand how a shared site coordination in Rhino. As you can see in the screen shot, 1 and 2 are the same thing in each model space, but what the 3rd location(seems to be the survey point of linked file) is related to.

You’ll want to cast to plane, which has rotational information (use Orient3D Component for a plane plane transformation).

It is a better way to show it, but, Japhy, what is that Shared Site plane. Is it a transitioning plane for the linked project or the survey point plane ?

I think I found what it is. It is the Survey “Plane” of the linked file in the actual model space.