Represents the "Namespaces" entry of the structure tree root object.

It is defined as part of the PDF 2.0 specification.

It contains an array which contains NamespaceElements.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 322, page 557.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 354, page 720.

The Namespaces entry holds an array of namespace objects used by structure elements. Every namespace referenced by a structure element NS entry must appear in this array.