Represents the "IF" entry of the fdf field dictionary object.

It is an optional entry defined as part of the PDF 1.3 specification.

It contains an IconFitElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 246, page 462.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 249, page 560.

The icon fit dictionary controls how the button icon referenced by AP is scaled and positioned within the widget rectangle of the target field.