The Reference Index shows all uses of a particular reference (both inputs and outputs) within a module. It can be accessed in many different ways, including by clicking on an input or output reference, or by clicking on a particular item in the Module Reference Index. Clicking on any item in the Reference Index will cause the corresponding document to be displayed in the content pane. The single output reference is shown in red in the Reference Index.
This same selection in Treeview format would look like this: