Represents the "D" entry of the optional content properties dictionary object.

It is a required entry defined as part of the PDF 1.0 specification.

It contains an OptionalContentConfigElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 100, page 229.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 98, page 281.

The D entry holds the default optional content configuration dictionary. It sets the initial on/off state for all groups when the document is first opened and defines the user interface behaviour of the layer panel.