A great idea: tag blocks of text in a PDF and build them into reading order, so that they can be read out loud. How well does that work, then?
One of the more confusing features of PDF apps, as none seems to work quite the same, and removing them isn’t quick or simple.
Tables of Contents, Outline, Bookmarks: what’s the difference, and how portable are they in PDF?
Three ways to remove data from PDFs: redaction, deletion of content, and deletion of annotations. Can you trust them, or do they leak data?
Do you use digital signatures in PDF documents, or do you trust your PDF reader to check them? You could be spoofed into trusting forgeries.
For around half the cost of a year of Adobe Acrobat Pro DC, you can have a superb PDF reader with good general annotation and editing tools.