Tag Tree: The PDF's Hidden HTML Skeleton

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Adapted from HHS.GOV, Section 508 Guide Tagging PDF's in Adobe Acrobat Pro

PDF tags provide a hidden structured textual representation of the PDF content that is presented to screen readers. For example, documents that have visual lists can be tagged with list tags, documents that have visual data tables can be tagged with table tags, etc. They exist for accessibility purposes only and have no visible effect on the PDF file. When a PDF is created from a Microsoft Word document, initial tags will be generated based on the content and formatting of the Microsoft Word document.

If your word processing document is correctly formatted, this should automatically create a tagged PDF.

 

Yes, the semantic structure is very similar. Compare the PDF Tag Panel to the left and the HTML  tags below. What do you notice? One of the best accessibility aids a screen reader user can have is a good content structure of headings, paragraphs, lists, etc. A good HTML semantic example might look something like the following:

HTML Semantic Text Content Example

<h1>My heading</h1>

<p>This is the first section of my document.</p>

<p>I'll add another paragraph here too.</p>

<ol>
  <li>Here is</li>
  <li>a list for</li>
  <li>you to read</li>
</ol>

<h2>My subheading</h2>

<p>This is the first subsection of my document. I'd love people to be able to find this content!</p>

<h2>My 2nd subheading</h2>

<p>This is the second subsection of my content. I think is more interesting than the last one.</p>

 

 

 

Screen readers follow the Tags Panel structure. It is essential for the tag panel to be in logical reading order. Editing the document's tag panel will impact the reading order of surrounding elements. For example, if an image is added, the document's tag panel will need to be reviewed to ensure the proper reading order is maintained.

Remediating an inaccessible PDF is labor-intensive. The more complex the PDF, the more effort and time is required.