The output intent subtype. This key is required. The value of this key must be a CFString object equal to "GTS_PDFX"; otherwise, the dictionary is ignored.
Available in Mac OS X v10.4 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)