Represents the "Parent" entry of the pop-up annotation object.

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

It contains an AnnotationElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 183, page 406.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 186, page 492.

The parent entry must reference the markup annotation that owns this pop-up. The pop-up carries no content; all text and author information comes from the parent markup annotation's Contents and T entries.