Represents the "PreserveRB" entry of the set-ocg-state action object.

It is an optional entry defined as part of the PDF 1.0 specification.

It contains a bool representing a PDF boolean object.

The PDF specification states that this item assumes a value of true if no value has been provided.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 213, page 427.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 217, page 519.

When true and a targeted group belongs to a radio-button group, the action maintains the constraint that exactly one member of the group is visible. When false the constraint is ignored.