HP 815MFP - Manual (Page 94)

88 hp designjet 815mfp & scanner 4200
The paper frame gives a complete “What You See Is What You
Get” (WYSIWYG) impression of your copy.
The frame’s visual outer boundaries are determined by the Input size
setting. The area inside the frame shows what will be copied.
The frame’s thickness visualizes the margins in relation to the copy’s
size and shows how they crop the image. With margins at the value
of zero, a thin frame will still be displayed to show the capture area.