PDF Accessibility Checker and accessible PDF - why PAC Testing is not enough

In this post, I would like to clear up a few misunderstandings about the PDF Accessibility Checker (PAC) and accessible PDFs. First of all: A PDF that is error-free according to PAC does not have to be accessible. Conversely, a PDF that works without problems with assistive technology does not have to be error-free in the PAC.

This post is also to be understood as a criticism of the developers of PAC. I wish they communicated the purpose and limitations of their tool more clearly. It doesn't make sense why the thing wasn't called PDF UA Checker, that would be more appropriate. The reason for this criticism is that many persons - usually non-disabled persons - chase a PDF through the PAC and knock the results out of a user's ears. We internally call this the idiot test, the tester doesn't have to know anything about PDF to perform this test and only counts red crosses and green ticks. Awesome, you can hit a few buttons, you're a PDF accessibility pro!

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Does PAC check the accessibility of a PDF document?

PAC mainly checks technical structures. All content of a PDF must be tagged, i.e. enclosed in containers. Metadata, alternative text for images and a few other criteria should be met.

These tags must be stored according to the technical standard for accessible PDFs PDF Universal Accessibility (PDF UA). This is exactly what PAC checks, no more and no less.

In theory, that should be enough. In practice, however, there are other problems that actually only become apparent in conjunction with assistive technology.

Unfortunately, it always has to be said: PDF UA is not the standard for accessible PDF. In this respect, a PAC test cannot say anything about the accessibility of a PDF. It can only say that a PDF is PDF-UA-compliant or that the structure meets certain requirements. According to all guidelines such as EN 301 549 or the American Section 508, the WCAG is the standard for accessible PDF. PDF UA is a way, but not a requirement, to achieve WCAG compliance. Unfortunately, the responsible PDF Association also communicates incorrectly here - probably intentionally. At the end of the day, the manufacturers of the tools are sitting in these mergers, who – how could it be otherwise – primarily want to sell their tools. Why are there extensions for InDesign or Acrobat Pro at all when Adobe manages the standard? Why are these extensions more expensive than their vehicles?

PAC is obsolete

Unfortunately, the current version 3 of the PAC is outdated. It is based on an older PDF standard. The current standard for PDF is 2.0. However, PDF 2.0 contains elements that PAC does not know and therefore marks as incorrect. Since the PAC 3 is now several years old, the question arises as to why there is no update. Unfortunately, the new PAC 2021 does not solve all problems but create some new.

What about Office documents?

With the on-board resources of Microsoft Office and Libre Office, it is currently not possible to create PDFs that pass the PAC check. Expensive additional tools are necessary for this, but they do not provide any significant added value, except that they are PDF-UA-compliant, which, as I said, says nothing about their usability for disabled persons. axesPDF, for example, corrects a few technical errors that most users would not have noticed anyway, the high price for this extension above all gives you a good conscience.

As a rule of thumb: What can be created using the Office packages can also be made accessible with Office. What PAC says about it doesn't matter for now. Conversely, hardly anyone would think of using Office to make a brochure created in Quark Express or InDesign accessible.

Post-processing with Adobe Acrobat Pro is time-consuming and does not add any value to Office documents in relation to the effort involved. The resources required for this can be used elsewhere.So what is the gold standard?

The only criterion that counts in terms of accessibility is the specific person. The standards, called WCAG, PDF UA or Din 18040, are tools so that we don't have to reinvent the wheel every time. But if the disabled person is not coping, the reference to the standard is not appropriate.

So is PAC useless?

no way. Aside from the fact that PAC itself can contain bugs, it is a tool for experienced desktop publishers. For persons who don't really know what an accessible PDF is, however, the tool creates more confusion than clarity. Therefore, leave the checking of your documents to professionals or persons who need accessibility. PAC is not a useful tool for laypersons and certainly not a seal of approval for accessible PDFs.

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