Represents the "Shading" entry of the type 2 pattern dictionary object.

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

It contains a ShadingElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 76, page 181.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 75, page 225.

The Shading entry references a shading dictionary or stream that defines the color gradient to be painted. The shading type, color space, and function together determine how color varies across the painted area.