Represents the "BBox" entry of the artifact attributes object.

It is an optional entry defined as part of the PDF 2.0 specification.

It contains a RectangleElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 385, page 787.

The BBox entry gives the artifact bounding box in default user space as a four-element array. Accessibility tools use this to identify and exclude artifact content from the logical reading order.