Represents the "Extend" entry of the type 2 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: 80, page 186.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 79, page 231.

The Extend array contains two booleans. The first controls whether the starting color extends beyond the start point of the axis; the second controls whether the ending color extends beyond the end point. When true for an endpoint, the terminal color fills the area on that side indefinitely.