In the External References Manager, you can view a list of external references that exist in a product and examine which items (such as faces and edges) are involved in each external reference.
Context:
Note:
In the design tree, indicates items that have external references.
From the Assembly section of the action bar, click External References Manager .
In the dialog box, click Update All References to incorporate any recent changes.
In the list, you can do the following:
Expand items to see geometry involved in the external reference.
Select items to highlight them in the design tree and work area.