Represents the "Instance" entry of the 3d node dictionary object.

It is defined as part of the PDF 1.7 Extension Level 3 specification.

It contains a RichMediaInstanceElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 312, page 538.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 323, page 671.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 9.47, page 58.

The Instance entry holds the instance name as a byte string when the named node appears more than once in the model hierarchy. It distinguishes a specific instance from other instances of the same named node.