Represents the "Group" entry of the page object object.

It is an optional entry defined as part of the PDF 1.4 specification.

It contains a GroupAttributesElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 30, page 78.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 3.27, page 23.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 31, page 104.

The Group entry references a group attributes dictionary that designates the page as a transparency group. This controls how the page's content composites when the page is used as a source in a transparency group rendering.