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Checkpoint 14High Priority7 failure conditions

Checkpoint 14: Headings

Headings must be properly tagged and follow a logical hierarchy so users can navigate and understand document structure.

Related WCAG:1.3.12.4.6

Checkpoint 14: Headings

Headings must be properly tagged and organized in a logical hierarchy. This allows users to understand document structure and navigate quickly to the content they need.

What This Means

Headings serve two critical purposes in accessible PDFs:

  1. Structure: They organize content into sections and subsections
  2. Navigation: Screen reader users can jump directly from heading to heading

PDF/UA requires headings to use specific tags:

  • H1 through H6 for numbered heading levels (like HTML)
  • Or the generic H tag with nesting to indicate levels

Headings must follow a logical hierarchy. You cannot skip from H1 directly to H4. Each level should be nested within the previous level, creating a clear outline of the document.

Why It Matters

For sighted users, headings are visual landmarks. Large, bold text signals new sections. For screen reader users, headings are the primary navigation tool:

  • Jump to headings: Users press "H" to move from heading to heading
  • Navigate by level: Users can jump to all H2s or all H3s
  • Understand structure: The heading outline shows document organization
  • Save time: Users can skip directly to relevant sections

Without proper heading structure:

  • Screen reader users must listen to entire documents sequentially
  • Document structure is invisible to assistive technology
  • Users cannot efficiently find information
  • Navigation features in PDF readers do not work

Common Violations

The Matterhorn Protocol defines seven failure conditions for headings.

14-001: Headings Are Not Tagged (Human Testing)

What's Wrong: Text that visually appears as a heading (large, bold, separated from body text) is not tagged with a heading tag. It might be tagged as a paragraph (P) or have no tag at all.

How to Identify:

  • Compare visual appearance to tag structure
  • Look for large, bold text tagged as P
  • Use screen reader navigation (press H) and check if all sections are reachable
  • Visual headings that do not appear in the Tags panel as H or H1-H6

How to Fix in Adobe Acrobat:

  1. Open the Tags panel
  2. Find the incorrectly tagged heading text
  3. Right-click and select Properties
  4. Change the Type from "P" to the appropriate heading level (H1, H2, etc.)
  5. Click Close

14-002: First Heading Tag Is Not H1 (Machine Testable)

What's Wrong: The first heading in the document is not an H1. The document might start with H2 or another level, which breaks the heading hierarchy.

How to Identify:

  • PDF/UA validators will flag this automatically
  • Open the Tags panel and expand to find the first heading
  • Check if it is H1

How to Fix:

  1. In the Tags panel, locate the first heading
  2. Right-click and select Properties
  3. Change the Type to "H1"
  4. Adjust subsequent headings if needed to maintain logical hierarchy

Structural example:

Incorrect:         Correct:
- H2 Introduction  - H1 Document Title
- H3 Background    - H2 Introduction
- H2 Methods       - H3 Background
                   - H2 Methods

14-003: Numbered Heading Levels in Descending Sequence Are Skipped (Machine Testable)

What's Wrong: The heading hierarchy skips levels. For example, an H1 is followed directly by an H3, with no H2 in between. Or an H2 is followed by an H5.

How to Identify:

  • PDF/UA validators detect this automatically
  • Review the Tags panel for heading sequence
  • Create an outline view and check for gaps

How to Fix:

  1. Review the document outline in the Tags panel
  2. For each skipped level, either:
    • Change the incorrect heading to the proper level, or
    • Add the missing intermediate headings
  3. Ensure the sequence follows: H1 > H2 > H3 > H4 > H5 > H6

Examples:

Incorrect:              Correct:
- H1 Title              - H1 Title
  - H3 Section (skip!)    - H2 Section
    - H4 Detail             - H3 Detail

Incorrect:              Correct:
- H2 Chapter 1          - H1 Document
  - H5 Detail (skip!)     - H2 Chapter 1
                            - H3 Section
                              - H4 Subsection
                                - H5 Detail

14-004: Numbered Heading Tags Do Not Use Arabic Numerals (Human Testing)

What's Wrong: Heading tags use non-standard numbering like Roman numerals (HI, HII) or words (HeadingOne) instead of standard H1, H2, H3, etc.

How to Identify:

  • Review tag names in the Tags panel
  • Look for non-standard heading tag names
  • This may appear if the document uses a non-standard role map

How to Fix:

  1. In the Tags panel, find the non-standard heading tags
  2. Right-click each one and select Properties
  3. Change the Type to standard heading tags: H1, H2, H3, H4, H5, or H6
  4. If there is a role map issue, also fix the role mapping (see Checkpoint 02)

14-005: Content Representing 7th Level Heading Does Not Use H7 Tag (Human Testing)

What's Wrong: The document has content that functions as a seventh-level heading, but it is not tagged as H7. While PDF/UA typically uses H1-H6, documents with very deep nesting should use H7 for seventh-level headings.

How to Identify:

  • Look for content visually formatted as a seventh level of heading
  • Check the tag structure for deeply nested sections
  • This is rare but occurs in technical documents

How to Fix:

  1. In the Tags panel, find the seventh-level heading content
  2. Right-click and select Properties
  3. Change the Type to "H7"
  4. Note: Some tools may require adding H7 to the role map

Document structure guidance:

  • Most documents should not need more than 4-5 heading levels
  • If you need H7+, consider restructuring the document
  • Alternatively, very deep content might be better as lists or tables

14-006: A Node Contains More Than One H Tag (Machine Testable)

What's Wrong: A single structure element (tag) contains multiple heading tags inside it. Each section should have only one heading that titles it.

How to Identify:

  • PDF/UA validators will detect this
  • Look in the Tags panel for parent tags containing multiple headings

How to Fix:

  1. Locate the parent tag with multiple headings
  2. Restructure so each section has one heading:
    • Create separate section tags (Sect or Div)
    • Move each heading into its own section
  3. Ensure the document structure reflects logical sections

Example fix:

Incorrect:              Correct:
- Sect                  - Sect
  - H2 First              - H2 First
  - H2 Second             - P Content...
  - P Content...        - Sect
                          - H2 Second
                          - P Content...

14-007: Document Uses Both H and Numbered H Tags (Machine Testable)

What's Wrong: The document mixes the generic H tag with numbered heading tags (H1, H2, etc.). PDF/UA requires consistency: use either all numbered headings OR all generic H tags (with nesting to show levels), not both.

How to Identify:

  • PDF/UA validators will flag this error
  • Search the Tags panel for both "H" and "H1"/"H2"/etc.
  • This often happens when combining content from different sources

How to Fix:

Option 1: Convert all to numbered headings (recommended)

  1. Find all generic H tags in the Tags panel
  2. For each H tag:
    • Determine its level based on document context
    • Right-click > Properties
    • Change Type to H1, H2, H3, etc.

Option 2: Convert all to generic H with nesting

  1. Find all numbered heading tags
  2. Change each to generic H
  3. Ensure proper nesting within the tag tree to indicate levels

Numbered headings are generally preferred because they are more explicit and work better with most assistive technology.

How to Fix in Adobe Acrobat

Viewing Heading Structure

  1. Open View > Show/Hide > Navigation Panes > Tags
  2. Expand the tag tree
  3. Look for H, H1, H2, H3, H4, H5, H6 tags
  4. Compare to visual document appearance

Using the Reading Order Tool

  1. Go to Tools > Accessibility > Reading Order
  2. Numbered regions show content order
  3. Click on a region and select a heading level button (Heading 1, Heading 2, etc.)
  4. This creates properly tagged headings

Changing Existing Heading Levels

  1. In the Tags panel, find the heading tag
  2. Right-click and select Properties
  3. Click the Tag tab
  4. In the Type dropdown, select the correct heading level
  5. Click Close

Checking with Accessibility Checker

  1. Go to Tools > Accessibility > Accessibility Check
  2. Run the full check
  3. Look for "Appropriate nesting" and heading-related issues
  4. Click on issues to navigate to problems

Creating Document Outline from Headings

Properly tagged headings can generate bookmarks automatically:

  1. Go to View > Show/Hide > Navigation Panes > Bookmarks
  2. Click the Options menu (hamburger icon)
  3. Select New Bookmarks from Structure
  4. This creates a navigable bookmark tree from your headings

How to Fix in Microsoft Word

Creating proper heading structure in Word before PDF conversion is the most effective approach.

Using Built-in Heading Styles

  1. Select the text that should be a heading
  2. On the Home tab, find the Styles gallery
  3. Click the appropriate heading style:
    • Heading 1 for main document title
    • Heading 2 for major sections
    • Heading 3 for subsections
    • Continue through Heading 4, 5, 6 as needed
  4. Do NOT just make text bold and larger; use the styles

Viewing Document Structure

  1. Go to View > Navigation Pane
  2. Click the Headings tab
  3. Review the document outline
  4. Check for:
    • Proper hierarchy (no skipped levels)
    • All sections represented
    • Consistent use of levels

Fixing Fake Headings

If headings were created with manual formatting:

  1. Select the fake heading text
  2. Apply the correct Heading style
  3. Adjust the style's formatting if needed (right-click style > Modify)
  4. Never use manual formatting for headings

Customizing Heading Appearance

If you want headings to look different than the default:

  1. Right-click the Heading style in the Styles gallery
  2. Select Modify
  3. Change font, size, color as desired
  4. Click OK
  5. The style still maps correctly to PDF heading tags

PDF Export Verification

  1. Save as PDF with accessibility options enabled
  2. Open in Acrobat
  3. Check the Tags panel for proper H1-H6 structure
  4. Run the Accessibility Checker to verify

Testing Your Fix

Automated Testing

Adobe Acrobat:

  1. Go to Tools > Accessibility > Accessibility Check
  2. Run with PDF/UA-1 selected
  3. Check for heading-related issues

PAC (PDF Accessibility Checker):

  1. Open the PDF in PAC
  2. Run the PDF/UA check
  3. Review Checkpoint 14 results
  4. Check all seven failure conditions

Screen Reader Testing

  1. Open the PDF with a screen reader
  2. Press H repeatedly to jump through headings
  3. Verify:
    • All sections are reachable
    • Heading levels are announced correctly
    • Structure makes sense when navigating by heading
  4. Test 1-6 keys to jump to specific heading levels

Manual Review

  1. Create a document outline from headings
  2. Compare to visual document appearance
  3. Verify:
    • First heading is H1
    • No levels are skipped
    • Structure is logical
    • All visual headings are tagged

Validation Checklist

  • All headings are properly tagged (H1-H6)
  • First heading is H1
  • No heading levels are skipped
  • Using numbered headings (H1-H6), not generic H
  • Each section has only one heading
  • Visual headings match tag structure
  • Screen reader navigation works correctly

Additional Resources

Official Standards and Guidelines

Tutorials and Guides

Tools

This documentation is based on the Matterhorn Protocol 1.02, the definitive reference for PDF/UA validation. For the most current information, consult the PDF Association and W3C WCAG guidelines.

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