Represents the "TF" entry of the media permissions dictionary object.

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

It contains a string representing a PDF string object.

This is encoded as a string using single byte ASCII encoding.

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

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 275, page 494.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 286, page 619.