To Hide and Show PDF Underlay Frames

Do the following:

To hide frames, set the PDFFRAME system variable to 0. With this setting, the PDF underlay frame is hidden.
The frame temporarily reappears during selection preview or object selection.
To display and plot frames, set the PDFFRAME system variable to 1. With this setting, you can display and plot the PDF underlay frame.
To display frames without plot, set the PDFFRAME system variable to 2. With this setting, you can display but not plot the PDF underlay frame.