Represents the "XFA" entry of the interactive form dictionary object.

It is an optional entry defined as part of the PDF 1.5 specification. It was deprecated in PDF 2.0.

This property may contain one of two different types:.

1) An array which contains Elements.

2) A StreamElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 218, page 431.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 224, page 526.