Use the PDFUnderlayOptions command to set EntitySnap access to PDF Underlay entities and control the frame visibility of PDF Underlays.
To control EntitySnap access to PDF Underlays:
To control frame visibility of PDF Underlays:
If the ribbon is active, select a PDF underlay in the graphics area and control the frame visibility from the contextual ribbon tab: click PDF Underlay > Reference Manager > PDF Underlay frame Mode.
Access
Command: PDFUnderlayOptions