Represents the "Suspects" entry of the mark information
It is an optional entry defined as part of the PDF 1.6
specification. It was deprecated in PDF 2.0.
It contains a bool representing a PDF boolean object.
The PDF specification states that this item assumes a value of
false if no value has been provided.
For definitive details see:.
The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 321,
The ISO PDF
Specification, ISO 32000-2:2017 PDF 2.0; Table: 353, page 719.