PDF accessibility requires an understanding of how users with disabilities access electronic information and how electronic documents (such as PDF documents) function with assistive devices used by individuals with disabilities. The challenge is to provide the most convenient access to electronic information by removing obstacles that prevent accessibility tools from functioning effectively.
What is PDF accessibility?
Web Content Accessibility Guidelines (WCAG 2.0) is a comprehensive set of guidelines for making web pages and posted content (like PDFs) accessible to a wide range of users with disabilities — blindness, low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photo-sensitivity, and any combination thereof.
Canadian federal government requirements
In 2011, the Government of Canada’s Standard on Web Accessibility came into effect. This means that all government organizations that post content on the web are required to follow these standards, which are based on WCAG 2.0. These guidelines cover a wide range of recommendations for making web content more accessible for users.
The Government of Canada requires Level AA conformance, which refers to colour contrast, text control, alternative text for contextual graphics, headings and tags, language, and navigation and reading order.
Principles of accessibility
Content and user interface components must be presented in a way that enables the user to perceive them by ensuring they are visible to a variety of senses (sight, touch, sound).
User interface components and navigation must not require an interaction the user cannot perform.
All users must be able to read and understand the content. This may be achieved through Alternative-Text.
Content must be robust enough that it can be interpreted reliably by assistive devices, even as technologies evolve.
Tips + tricks
Abbreviations, acronyms and initialisms
Avoid using unpronounceable acronyms and initialisms in your document. If necessary, you’ll need to provide Expansion-Text (e.g., NRCan would require the Expansion-Text “Natural Resources Canada”).
Individuals who are blind, have low vision, or have cognitive disabilities require descriptive text in addition to captions or other contextual graphics. Descriptive text describes what you see when you look at the image or graphic. All of the Alternative-Text must be provided in entirety before an accessible PDF document can be created.
Under current guidelines, complex maps do not require extensive Alternative-Text; use a descriptive title instead.
Do not use colour to differentiate content in a document unless used in conjunction with other methods such as chapter numbering or naming. Ensure there is sufficient contrast between the text and background colour in accordance with WCAG 2.0 guidelines.
Avoid wording that directs users, such as “as shown on the right.” Instead, use specific wording such as “as shown in Figure 1.”
The Government of Canada has provided a list of exclusions from specific requirements (such as complex maps).
Avoid or limit use of footnotes, especially in tables. If your document has a lot of footnotes, endnotes are preferred.
Avoid use of text in graphic elements (logos are an exception). In circumstances where you have to include an image with text, you’ll need to include Alternative-Text for the image. Avoid rotating pages or content within a document if possible.
Bilingual documents do not follow accessibility guidelines, so avoid or limit the use of other languages within a single document.
Assistive devices don’t support many Aboriginal languages. As a result, documents made using Aboriginal languages and fonts need to be supplied along with a statement of partial conformance due to language.
Table of contents
Ideally, all accessible PDFs should contain a table of contents and PDF bookmarks. If this isn’t possible, bookmarks can be used alone.
Keep tables simple. Consider breaking up complex tables into multiple tables, avoid nested headers, and avoid using footnotes. Tables that run over multiple pages are accessible; however, tables that span pages horizontally are not accessible.
Provide the final version of text in its entirety, in one document, with all track-changes accepted.
Government of Canada Web Standards Office
For more information about how web accessibility standards affect your projects, contact:
Web Standards Office, Chief Information Officer Branch (Français)
Treasury Board of Canada Secretariat
Ottawa ON K1A 0R5