Represents the "IF" entry of the appearance characteristics dictionary object.

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

It contains an IconFitElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 189, page 410.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 192, page 497.