Displays options for attaching external references.

Summary
The External Reference visor is displayed when you select an external reference.
List of Options
The following options are displayed.
Edit Reference in Place
Edits the selected xref directly within the current drawing window. (REFEDIT command)
Open Reference in New Window
Opens the selected drawing reference (xref) in a new window. (XOPEN command)
Create Clipping Boundary
Crops the display of the selected external reference to a specified boundary. (XCLIP command)
Delete the Clipping Boundary
Removes the clipping boundary from the selected external reference. (XCLIP command)