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On 2/14/20 3:43 AM, Rik Kabel wrote:
[...] The further I look into bookmark, annotation, and attachment handling by a number of viewers, the more confusing things appear.
Hi Rik, this is why following the prescription (the PDF spec) is better in order to check the standard than gathering information in different viewers.
And Acrobat still shows attachments twice under some circumstances, with the helpful flyover for one entry giving the location as the associated page number, and for the other giving it as the attachments tab.
That practice is explictly discouraged by the PDF Association, citing the behaviour of some viewers (but not naming Acrobat). See https://www.pdfa.org/wp-content/uploads/2018/10/PDF20_AN002-AF.pdf#search=us....
What is more troublesome on the ConTeXt side is the validation issue with the appearance dictionary for visible attachments.
This is my (educated?) guess: appearance dictionaries are required to print annotation icons. This isn’t especially directed to attachments, but to all annotation types (excepting popups and links).
The difference between validators when looking at the hidden attachment in my example hinges on the handling of the attachment mime type. I have filed a defect report with VeraPDF, which appears to be rejecting valid mime type that includes a charset clause.
If this is a bug, they should fix it. They may have missed a valid MIME type. Pablo -- http://www.ousia.tk