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

It is an optional entry defined as part of the PDF 1.0 specification.

It contains a BorderStyleElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 177, page 401.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 180, page 486.

The border style dictionary sets the width and dash pattern of the ellipse outline. The border is drawn centred on the inscribed ellipse boundary.