Represents the "RD" entry of the circle annotation object.

It is an optional entry defined as part of the PDF 1.5 specification.

It contains a RectangleElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 177, page 402.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 180, page 487.

The rect difference insets the actual ellipse from the annotation's Rect, providing visual space for a thick border or cloud arcs.