A Border zone uses existing page boxes.
This can be used for example to define a safety zone based on the trim box.
Set to Outside box and set the size to define a zone on the outside of the selected page box, or
Set to Outside box and set the size to define a zone on the outside of the selected page box, or
Set to Inside box and set the size to define a zone on the inside of the selected page box, or
Set to Centered on box and set the size to define a border centered on the edge of the selected page box