Represents the "Domain" 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 doubles, representing PDF numeric 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 Domain array gives the minimum and maximum parameter values passed to the function. The default is [0 1], mapping the start point to 0 and the end point to 1. Extending the domain beyond [0 1] allows the gradient to be extrapolated if Extend is also set.