Hi
Hi Ante,
For Aspose.Words, there is no direct way but you can use the How to Add Watermark example and set the color so light that it is not visible to human eye but still printable by high resolution printers.
For Aspose.Pdf, you can use annotations for this purpose as you can see in the following code
com.aspose.pdf.Document doc = new com.aspose.pdf.Document("c:/pdftest/Release.pdf");
com.aspose.pdf.FreeTextAnnotation annotation = new com.aspose.pdf.FreeTextAnnotation(doc.getPages().get_Item(1), new com.aspose.pdf.Rectangle(50, 600, 250, 650), new DefaultAppearance("Helvetica", 16,new java.awt.Color(255,0,0)));
annotation.setContents("ABCDEFG");
annotation.getCharacteristics().setBorder(new java.awt.Color(255,0,0));
annotation.setFlags(AnnotationFlags.Print | AnnotationFlags.NoView);
doc.getPages().get_Item(1).getAnnotations().add(annotation);
doc.save("c:/pdftest/Annotation_Added_34838-out.pdf");<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com:office:office" />
Best Regards,