Represents the "PMD" entry of the widget annotation object.

It is defined as part of the PDF 1.7 Extension Level 3 specification.

It contains a PaperMetaDataGenerationParametersElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 188, page 408.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 8.39, page 39.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 191, page 495.

The private metadata dictionary holds application-specific data not defined by the PDF specification, allowing custom information to survive round-tripping.