This 508 PDF Help Center lists many of the common errors and warnings encountered when using the popular free PDF Accessibility Checker (PAC) from Access for All, along with suggestions for resolving the errors and warnings using Adobe Acrobat Professional. PAC 2 was the first automated checker for PDF/UA compliance, and its successor, PAC 3, remains – in my opinion – the best one. The suggestions are specific to Acrobat Professional XI or, in some cases, DC, for Windows. The concepts should apply when using other versions, but the specific location of tools and features within Acrobat Pro may vary.
PAC 2 / PAC 3 Errors and Warnings
The following common PDF accessibility errors and warnings are shown in the order they are presented in the PAC 2 accessibility report, when sorted by Title. Click on a specific error or warning for details including suggestions for remediation using Adobe Acrobat Professional XI.
PDF/UA | Basic Requirements | Content | Artifacts and tagged content
PDF/UA | Basic Requirements | Content | Tagged content and artifacts
PDF/UA | Basic Requirements | Fonts | Font Embedding
PDF/UA | Basic Requirements | Natural Language of [X]
PDF/UA | Logical Structure | Alternative Descriptions | Alternative descriptions for annotations
PDF/UA | Logical Structure | Role mapping | Role mapping for standard structure types
PDF/UA | Logical Structure | Role mapping | Role mapping of non-standard structure types
PDF/UA | Logical Structure | Structure Elements | Annotations | Nesting of Link annotations inside Link structure elements
Link annotation is not nested inside a Link structure element
PDF/UA | Logical Structure | Structure Elements | Figures | Bounding Boxes
PDF/UA | Logical Structure | Structure Elements | Headings | Nesting of heading levels
PDF/UA | Logical Structure | Structure Elements | Notes | ID entry in Note structure elements
PDF/UA | Logical Structure | Structure Elements | Tables | Table regularity
PDF/UA | Logical Structure | Structure Tree | Document structure elements
Document structure element found which is not a root element
PDF/UA | Logical Structure | Structure Tree | [X] structure element
PDF/UA | Metadata and Settings | Document settings | Display of document title in window title
PDF/UA | Metadata and Settings | Document settings | Tag suspects
PDF/UA | Metadata and Settings | Document settings | Tab order entry in page with annotations
PDF/UA | Metadata and Settings | Metadata | “dc:title” in document’s XMP metadata
PDF/UA | Metadata and Settings | Metadata | PDF/UA identifier | PDF/UA identifier
Errors Requiring Human Inspection
The following common PDF accessibility errors are not detected by PAC – human inspection is required.
ListNumbering attribute for ordered list
Table header cell not tagged as a header
Non-table content tagged as a table
Etc…