PDF Accessibility Software FAQsResources for CommonLook's PDF Accessibility Suite

Every industry has its own lexicon of words, terms, acronyms, and definitions. The same is true for digital accessibility. For a layman or beginner in this industry, learning the vocabulary can be overwhelming.

Below are answers to some of the most commonly asked questions of digital accessibility.

Document and PDF Accessibility: The Basics

What is an accessible PDF?

A PDF document is considered truly accessible if it can be used/accessed by all users, including people with disabilities. For a PDF to be considered accessible, it should be compliant to accessibility standards, including WCAG 2.0, WCAG 2.1, Section 508, and PDF/UA.

While it is technically possible for a PDF to be accessible and not meet the accessibility standards, only the most basic of documents would apply. The standards were developed to ensure that documents work well with screen readers and other assistive technology.

Read more about accessible PDFs here.

What is the difference between PDF and accessible PDF?

An accessible PDF document can be navigated and accessed by everyone, including people with disabilities; this includes access for people who are blind, visually or cognitively impaired, or color-blind. If a PDF document is not created or remediated for accessibility to everyone, it is considered inaccessible.

Read more.

How to check if a PDF is accessible?

To check if a PDF is accessible, you can use CommonLook PDF Validator - A 100% FREE and complete plugin for testing and verifying PDF Accessibility.

You can download it here.

Screenshot of comprehensive PDF Validator Report

What is a PDF Accessibility Checker? What does it really do?

Simply put, it’s software that tests whether a given PDF document is accessible or not. CommonLook PDF Validator is a powerful PDF accessibility checker.

Read more about PDF accessibility checkers here.

Is there a glossary of terms related to PDF accessibility?

Yes, there are many terms related to document and PDF accessibility that anyone working in this industry should be aware of. We have drafted a white paper that contains 40 terms you should know if you work in this field.

You can download the 40 PDF Accessibility Terms Glossary white paper here. It’s FREE!

Document and PDF Accessibility: Technical

What are Tags in PDF?

Tags provide assistive technologies with an outline or structure of the PDF that interprets the content and its reading order to users. This outline is hidden from sighted viewers unless they open up the tag sidebar menu.

screenshot of the tags tree of a pdf document

What is a Tagged PDF?

A tagged PDF is a PDF document that contains tags. Tags provide a logical structure that governs how the content of the PDF is presented through assistive technology. A properly tagged PDF, therefore, becomes accessible to everyone.

Aside from making the PDF accessible, a tagged PDF has a few other advantages. For example, the content of a tagged PDF reflows seamlessly on devices with smaller screens, like smartphones and tablets.

A tagged PDF helps keep track of where items are in a particular document. This simplifies the review of workflows in documents.

Read more about tagged PDFs here.

What is PDF reading order?

Reading order is the order or sequence that assistive technologies (AT), like screen readers, present content to consumers. The tags in a PDF, or the Tags tree, present the logical structure of the document. The tag tree also includes the tag types that we all know and love – Headings, Lists, Tables, Figures, etc. By itself, this does not dictate reading order.

Read more about PDF reading order here.


Screenshot showing the last P tag in the correct reading order open for a landmark in the Tags tree (and its text highlighted in the physical view). The next text, currently in the wrong reading order, is also highlighted.

How to tag lists in PDF?

Tagging lists properly in a PDF is important. And sometimes it’s difficult. For example, when a screen reader finds an <L> (list) tag in the Tags tree, it will inform the user of the existence of a list, how many items are in the list and when the list has ended. It is much easier to skip list tags and just leave the content in paragraph tags, but this is not only semantically inaccurate but it also negatively impacts the end user's experience.

Read more about tagging lists in PDF here

Close-up of a PDF document's list tags


We update our FAQs regularly with new questions and answers. So, stay tuned!