Represents the "BBox" entry of the standard layout attributes object.

It is defined as part of the PDF 1.0 specification.

It contains a RectangleElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 343, page 597.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 378, page 770.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 344, page 600.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 379, page 774.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 345, page 604.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 380, page 778.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 346, page 608.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 381, page 782.

The BBox entry gives the element bounding box in default user space as a four-element array. It is used for absolutely positioned elements or those outside normal block flow.