Represents the "Ref" entry of the form XObject dictionary object.

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

It contains a ReferenceElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 95, page 219.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 4.45, page 27.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 93, page 269.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 363, page 632.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 399, page 812.

The Ref entry identifies an external page that this form XObject represents within the reference XObject mechanism. It carries a file specification and page identifier so the reader can resolve the reference to the actual external page content.