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What is PDF UA?

Some areas of accessibility lack specific guidelines and applications from WCAG 2.0. This can leave decisions of accessibility up to the interpretations of the developer. PDF Universal Accessibility is not one of those areas.

There are very clear technical specifications that need to be followed to maximize PDF accessibility. PDF accessibility falls under the WCAG 2.0 category of content creation. There is an International Organization for Standardization that has published a standard for PDF accessibility. This is ISO 14289-1. This technical specification covers all aspects of PDF document and application accessibility.

It is extremely frustrating for people who use assistive technology to not be able to fully access PDFs. PDFs are one of the more challenging resources to make fully accessible. At the same time, they are one of the most popular ways to make information available digitally. After reading this blog post, you should feel confident in your increased awareness of how to make PDFs fully accessible.

History of PDF UA

PDFs were originally created by Adobe Systems Incorporated as a way to share information in its original form. From the beginning, this format was completely inaccessible to the larger number of users who are dependent on some form of assistive technology. This is due to the fact that it was created focusing only on the visuals of documents. Starting in 2001, organizations placed a dedicated effort on increasing the accessibility of PDFs.

How is PDF/UA different than PDF/A

PDF/UA is not the only attempt to make PDF documents accessible. There is also PDF/A specification. The primary difference between the two is that PDF/UA has a stricter set of requirements than PDF/A. They are similar because both standards are primarily concerned with making sure that the semantic content of the document is not lost on people who have to use assistive technology.

PDF File Requirements

When creating content, it will fall under one of two categories. It will either be meaningful or decorative. Decorative content does not add any substantive value to the information presented and it can simply be marked as decorative when making the PDF accessible. By contrast, meaningful content needs to be organized and placed into an overall tag structure tree. When making the tag tree make sure to:

  • Tag content in a way that makes sense semantically;
  • Organize the structure tree in a way that aligns with how the document would be read;
  • Use only tags that were defined in PDF 1.7;
  • Provide an explanation for information that provides meaning through font formatting or page positioning;
  • Convert any visual images into text, or provide a text-based equivalent in the image’s properties;
  • Ensure that the language of the document is defined properly and that language changes are indicated in the text’s properties;
  • Add a title to the document’s properties; and,
  • Ensure that every single image has alternative text attributed to it.

PDF/UA extends beyond making files accessible. IT also sets out guidelines for how PDF programs and assistive technology have to be designed in order to read PDF documents. These aspects are critically important because it means that the broader system in which PDF documents exist is built to work with the PDFs.

PDF/UA Document Creation

It is much easier to create a PDF document to be UA from the beginning. It is possible to make a PDF accessible after the fact, but this is harder to do. There are many systems that allow for the creation of UA compliant PDFs. Not many applications fulfill all of the UA requirements and it is important to select a system that works for you.

PDF Font Requirements

When creating a PDF, it is imperative that the fonts are embedded into the PDF document. This means that all of the font information is actually stored in the PDF document. This ensures that no matter what fonts or programs are installed on the end users computer, that they can still read the information as it was originally designed.

What is a Structure Tree?

What does it mean for a PDF document to be tagged in a way that makes sense semantically? It requires that a tag hierarchy be created at the same time that the document is being created. Creating a tagged PDF is really similar to creating a structured webpage using semantic HTML markup. For example, the tag must appear in a certain order and nested inside or outside of other tags

PDF Program Accessibility

After you make a document completely accessible, it has to go into a software or program that actually reads the PDF. It is the responsibility of these programs to read the PDF and transfer fully all of the information, both visible and invisible, that is part of the PDF. A PDF reader needs to make sure the content is transmitted structurally sound and that navigation is intuitive by either the page number, tree, or bookmarks.

PDF Assistive Technology Compliance

People use a range of assistive technologies based on their need. Regardless of the type of assistive technology, they must be able to complete the tasks necessary to accurately deduce the meaning from a PDF document and communicate this meaning to the user.

This means that these assistive technologies need to be able to understand all of the information and read the document in a logical order. Two other requirements for assistive technologies are that they provide the user the freedom to navigate through the document in multiple ways and that the magnification of the document is easily changed.


To determine if a PDF document is UA, there are two methods of evaluation. These are automated and manual checks. Automated checks can evaluate the technical requirements but they cannot tell if the PDF’s content will makes sense to an assistive technology user. For example, they automated tools can tell if a document is tagged, and what order the tags are in, but not if that order is logical. Manual testing is also required to determine of text alternatives are truly equivalent to someone who cannot access the visual information.

PDFs are an extremely popular way to transmit information digitally. By creating a PDF but not ensuring that it works with assistive technology, is creating something that a large swath of users would be unable to use. PDF/UA helps content creation by providing a clear technical specification for creating accessible PDFs.

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