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Accessibility

An overview of best accessibility practices.

What is an accessible PDF?

PDF is a format or type of document. Its main purpose is to preserve the formatting of a document. According to WebAIM, an "accessible" PDF file generally refers to a  "tagged" PDF file. PDF tags provide a hidden, structured representation of the PDF content that is presented to screen readers. They exist for accessibility purposes only and have no visible effect on the PDF file. 

PDFs are typically created in one of two ways:

  • They are generated from scratch (e.g., from information in a database). The accessibility of these PDFs typically depends on the program or code creating the file.
  • Someone creates a source document first (e.g., in a Microsoft Word) and then converts it to a PDF. While the accessibility of these PDFs also depends on the programs used, the person who creates and converts the file has great control over the outcome. (WebAIM, 2022)

Checking PDFs for Accessibility

PDF documents are accessible if:

  • The information can be read by an assistive device such as screen reader
  • The document has a hierarchy of headings – for clarity and understanding
  • Lists, tables, and paragraphs are marked – so visual information is pragmatically available
  • Important images have informative Alt tags – so they are understandable when not seen
  • Unimportant images and graphics have empty Alt tags – so they can be skipped
  • Correct Tab order – keyboard-only user can follow the correct order
  • Metadata - Title, author, keywords etc. for discoverability

list adapted from https://it.ucsf.edu/how-to/accessible-pdf-best-practices

Creating Accessible PDFs

Creating Accessible Documents

Several programs support creating accessible documents keep their accessibility information intact when converted to PDF. These include Microsoft Office (Word, PowerPoint, or Excel), Adobe InDesign, LibreOffice, and OpenOffice.org.

The most popular of these tools—Microsoft Office—has good overall accessibility that continues to improve with each version. For example, a document created in Word should contain almost all the information necessary for an accessible PDF, including:

  • Headings
  • Alternative text for images
  • Table structure
  • Descriptive Links
  • Lists
  • Columns
  • Legible text size
  • Good contrast
  • No color reliance
  • Document title