PDF-MANUAL-VALIDATE
How to Fix the Problem
Manual Check Required
The accessibility errors detected in the file by WorldSpace Comply may not be comprehensive. Please conduct a manual analysis of the PDF file also.
Have the file reviewed by a user of assistive technology for reading order problems, tagging errors, and accessibility errors, and then repair them as needed. Whichever method you use to tag the PDF, use Acrobat to touch up the tagging and reading order for complex page layouts or unusual page elements. For example, the Add Tags To Document command can’t always distinguish between instructive figures and decorative page elements such as borders, lines, or background elements. It may incorrectly tag all of these elements as figures. Similarly, this command may erroneously tag graphical characters within text, such as drop caps, as figures instead of including them in the tag that represents the text block. Such errors can clutter the tag tree and complicate the reading order that assistive technology relies on.
Why it Matters
Without supplemental manual testing using assistive technologies such as screen reader software, it is not possible to completely verify the accessibility of PDF files because despite a high level of accuracy, no automated testing system can successfully identify ALL accessibility issues in all PDF files.
The Algorithm (in simple terms)
After checking the PDF file(s) against the automated rules for violations, when those detected might not be comprehensive, this "rule" reminds users to also conduct manual testing prior to concluding the accessibility evaluation.