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

It is defined as part of the PDF 1.0 specification.

It contains a NameTreeNodeElement containing StructureElementElements.

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 719.

The IDTree entry references the root of a name tree mapping element identifier strings to structure element objects. Any element with an ID entry can be located directly by its identifier.