Krita/PDFprinting
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< Krita
An informal specification of pdf/x-1a 2003 and pdf/x-3 2003 http://www.npes.org/standards/PDF-X-Application-Notes_V4-Sep06.pdf
A specification of pdf 1.4 (pdf/x is a subset of this) http://www.npes.org/standards/Tools/PDFReference_v1-4.pdf
Note that Qt is interrested in adding many(/all?) of these features as well.