Inplace Mates

I don't understand how an inplace mate works. I'll give youan example:

I have a top level assembly with a sub-assembly in it. Suppose Iedit the sub-assembly in the context of the top level assembly.Suppose I create a new part and I'm prompted for a plane. So I picka plane that exists in the Top level assembly. Now I have anin-place mate that references a plane that exists outside of thesub-assembly. This is fine and all but where is the externalreference indicator (->) for that mate? Do I automaticallyassume it created one? What is the behavior of such a mate in thiscondition?SolidworksAssemblies