PDFs

Accessibility Guidelines for Portable Document Formats (PDFs)

Linked PDFs are an extension of the Web site and should be fully accessible.

The following are some of the guidelines that should be validated for accessibility compliance for all PDF content:

• Accessible Text
• Acronyms and Abbreviations
• Alternative Text for Non-text Content
• Colour Contrast
• Document Access
• Language of Document
• Logical Structure
• Navigation

Please refer to the W3C's PDF Techniques for Web Content Accessibility Guidelines 1.0 and 2.0 for techniques and additional information concerning these checkpoints.

Accessible Text

Ensure that the text of the document is accessible.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 1 Ensure That the Text of the Document is Accessible
  • PDF Checkpoint 1.1 - Render Characters and Words in Reading Order within the Page
  • PDF Checkpoint 1.2 - Separate words explicitly with spacing characters.
  • PDF Checkpoint 1.3 - Use soft hyphens and hard hyphens appropriately.
  • PDF Checkpoint 1.4 - Use the ActualText attribute.
  • PDF Checkpoint 1.5 - Ensure that all characters codes map reliably to Unicode.

 

Acronyms and Abbreviations

Provide expansions for acronyms and abbreviations.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 7: Provide Expansions for Acronyms and Abbreviations

 

Alternative Text for Non-text Content

Alternative Text is additional or descriptive text that can be used to describe an image, formula, or other item in the document that does not translate naturally into text.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 2: Provide Text Alternatives for Images and Graphics

 

 

Colour Contrast

Ensure that text colour has an acceptable colour contrast ratio.

For most colours, 4.5:1 is an acceptable ratio, however for the red/orange colour range, a 7:1 ratio is recommended. There are various colour contrast checking tools available online (i.e. Colour Contrast Check by snook.ca).

WCAG Guidelines referenced:

• Guideline 1.4 Distinguishable: Make it easier for users to see and hear content including separating foreground from background.
  • 1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following: (Level AA)
    
    Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;
    
    Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.
    
    Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 4: Design for User Control of Color and Contrast
  • PDF Checkpoint 4.1 - Avoid drawing rectangles behind text that are not background elements.
  • PDF Checkpoint 4.2 - Text should not be placed on top of images.
  • PDF Checkpoint 4.3 - Avoid the use of Color as the Only Means to Convey Information

 

 

Document Access

Ensure the document permissions permit access.

Set the data access restrictions on the document to permit the contents to be accessed by assistive technologies.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 8: Set document protections to permit access

 

Language of Document

Identify the language of the document.

Use the language tagging facilities (Lang) to specify the natural language of all text in the document. (PDF 1.4)

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 5: Identify the Natural Language of all Text in the Document
  • PDF Checkpoint 5.1 - Identify the documents primary language.

 

Identify any changes in the document content's language.

In addition to identifying the primary language as above, individual elements containing content in a language other than main document language should be set to indicate a language change has occured on the page. Thus, this signals the screen-reader to switch to an alternate pronunciation scheme, or to identify alternative hyphenation schemes for various languages.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 5: Identify the Natural Language of all Text in the Document
  • PDF Checkpoint 5.2 - Identify when a language change occurs on the page.

 

 

Logical Structure

Properly structure content.

Properly nested headings and paragraphs enable the document's content to be easily read. Use tables for tabular data, lists for list data, etc.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 3: Provide Structural Grouping
  • PDF Checkpoint 3.1 - Provide logical structure (PDF Reference Manual Section 8.4.3) for the document.
  • PDF Checkpoint 3.2 - Tag artifacts in the page contents with the /Artifact marked content

 

Navigation

Facilitate document reading by providing a means for navigating the content.

WCAG PDF Checkpoint referenced:

• PDF Checkpoint 6: Document Navigation
  • PDF Checkpoint 6.1 - Use bookmarks to provide navigation aids into a document.
  • PDF Checkpoint 6.2 - Use links within a document.
  • PDF Checkpoint 6.3 - If the value of the link does not describe the target clearly and accurately, provide Alt attributes.
  • PDF Checkpoint 6.4 - Provide a clear, descriptive name for all form fields