Represents the "FontFile3" entry of the font descriptor object.

It is an optional entry defined as part of the PDF 1.2 specification.

It contains an EmbeddedFontStreamElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 122, page 283.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 120, page 342.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 124, page 285.

FontFile3 holds a font program whose format is identified by the Subtype entry in the stream dictionary. Common subtypes are Type1C for CFF-based Type 1 programs, CIDFontType0C for CFF-based CIDFonts, and OpenType for fonts in the OpenType container format.