Represents the "Extend" entry of the type 3 shading dictionary object.

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

It contains an array which contains bool representing a PDF boolean objects.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 81, page 187.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 80, page 233.