Checkpoint 11: Natural Language

Every piece of text in your PDF must have its language properly specified. This allows screen readers to use the correct pronunciation rules, making content understandable rather than garbled.

What This Means

Screen readers use text-to-speech engines that apply language-specific pronunciation rules. When the language is correctly specified:

• English text is spoken with English pronunciation
• French text is spoken with French pronunciation
• Spanish text is spoken with Spanish pronunciation

When language is not specified or is incorrect, screen readers guess or use default settings, often producing unintelligible speech. Consider how "chat" sounds in English versus French, or how a French screen reader would pronounce "Hello, how are you?"

PDFs must specify:

1. The primary language of the document
2. Language changes for any content in a different language

Why It Matters

Language identification directly affects whether users can understand content:

• Pronunciation accuracy: Screen readers apply different rules for each language
• Word boundaries: Languages handle word separation differently
• Special characters: Accented characters and symbols are pronounced based on language
• Comprehension: Incorrect pronunciation makes content unintelligible

For multilingual documents, proper language tagging is essential. A French paragraph in an English document needs to be marked as French, or screen reader users will hear nonsensical English pronunciation of French words.

Common Violations

The Matterhorn Protocol defines seven failure conditions for language specification.

11-001: Natural Language for Text in Page Content Cannot Be Determined (Machine Testable)

What's Wrong: The main text content of pages does not have a language specified. The document is missing the primary language setting.

How to Identify:

• PDF/UA validators will report missing document language
• In Acrobat, check File > Properties > Advanced > Language
• If the Language field is empty, this error exists

How to Fix in Adobe Acrobat:

1. Go to File > Properties
2. Click the Advanced tab
3. In the Language dropdown, select the primary document language
4. Click OK

How to Prevent in Microsoft Word:

1. Go to File > Options > Language
2. Set the correct editing language
3. The language carries over when exporting to PDF

11-002: Natural Language for Alt, ActualText, and E Attributes Cannot Be Determined (Machine Testable)

What's Wrong: Alternative text, actual text, or expansion text attributes do not inherit or specify a language. Screen readers cannot determine how to pronounce this content.

How to Identify:

• PDF/UA validators will flag this error
• Check alternative text on images in multi-language documents
• Review expansion text for abbreviations

How to Fix:

1. Ensure the document's primary language is set (see 11-001)
2. For content in a different language than the document:
   • In the Tags panel, locate the element
   • Right-click and select Properties
   • Set the language attribute for that specific tag

Example: An English document contains an image with French alt text. The Figure tag needs a French language attribute.

11-003: Natural Language in Outline Entries Cannot Be Determined (Machine Testable)

What's Wrong: Bookmarks (outline entries) in the PDF do not have language specified. Screen readers cannot pronounce bookmark text correctly.

How to Identify:

• Check the Bookmarks panel for multilingual bookmark titles
• PDF/UA validators will flag outline entries without language

How to Fix:

1. Ensure the document language is set (this provides default)
2. For bookmarks in a different language:
   • Use PDF editing tools or libraries to set bookmark language
   • Some advanced tools allow language specification per bookmark

Practical approach: Regenerate bookmarks from a properly tagged source document where heading languages are specified.

11-004: Natural Language in Contents Entry for Annotations Cannot Be Determined (Machine Testable)

What's Wrong: Annotation text (like comments, notes, or descriptions) lacks language specification.

How to Identify:

• Review annotations in the PDF
• Check if annotations are in different languages than the document
• PDF/UA validators will report this issue

How to Fix:

1. Set the document's primary language
2. For annotations in other languages, use PDF editing tools to set the language property on individual annotations

11-005: Natural Language in TU Key for Form Fields Cannot Be Determined (Machine Testable)

What's Wrong: Form field tooltips (the TU entry, which stands for "Tooltip" or "User-friendly name") do not have language specified.

How to Identify:

• Review form fields in the PDF
• Check if tooltips are provided in multiple languages
• PDF/UA validators will flag form fields with missing tooltip language

How to Fix in Adobe Acrobat:

1. Go to Tools > Prepare Form
2. Click on each form field
3. In the properties, check the Tooltip field
4. Ensure the document language is set for default language
5. For tooltips in other languages, advanced editing may be required

11-006: Natural Language for Document Metadata Cannot Be Determined (Machine Testable)

What's Wrong: Document metadata (title, author, subject, keywords) lacks language specification.

How to Identify:

• Check File > Properties > Description tab
• PDF/UA validators will report metadata language issues
• This is common when metadata is in a different language than content

How to Fix:

1. Set the document's primary language in File > Properties > Advanced
2. Ensure metadata is in the same language as the document
3. If metadata must be in a different language, advanced PDF editing tools can set metadata language separately

11-007: Natural Language Is Not Appropriate (Human Testing)

What's Wrong: A language tag is present, but it specifies the wrong language. For example, English text is tagged as French, or a French paragraph within an English document is not marked as French.

How to Identify:

• Listen with a screen reader in different sections
• Words pronounced with wrong accent/rules indicate incorrect language tagging
• Manually review language tags against actual content

How to Fix:

1. In the Tags panel, find elements with incorrect language
2. Right-click the tag and select Properties
3. Correct the Language setting
4. For the entire document, update File > Properties > Advanced > Language

How to Fix in Adobe Acrobat

Setting the Document Language

1. Open your PDF in Adobe Acrobat Pro
2. Go to File > Properties
3. Click the Advanced tab
4. Find the Language dropdown
5. Select the primary language of the document:
   • English (US): en-US
   • English (UK): en-GB
   • French: fr
   • Spanish: es
   • German: de
   • (and many others)
6. Click OK

Setting Language for Specific Content

For content in a different language than the document default:

1. Open the Tags panel (View > Show/Hide > Navigation Panes > Tags)
2. Locate the tag containing the different-language content
3. Right-click the tag and select Properties
4. Click the Tag tab
5. In the Language field, enter the appropriate language code:
   • French: fr or fr-FR
   • Spanish: es or es-ES
   • German: de or de-DE
6. Click Close

Checking Language with Accessibility Checker

1. Go to Tools > Accessibility > Accessibility Check
2. Run the full check
3. Look for issues under "Document" related to language
4. The checker will report if primary language is missing

Using the Reading Order Tool

The Reading Order tool can help identify untagged content that needs language specification:

1. Go to Tools > Accessibility > Reading Order
2. Review the document structure
3. Ensure all content is tagged
4. Add language attributes as needed to tags

How to Fix in Microsoft Word

Setting language correctly in Word before PDF conversion prevents most issues.

Setting Document Language

1. Select all text (Ctrl+A or Cmd+A)
2. Go to Review > Language > Set Proofing Language
3. Select the primary document language
4. Click OK

Marking Language Changes

For text in a different language:

1. Select the text in the other language
2. Go to Review > Language > Set Proofing Language
3. Select the appropriate language for that text
4. Click OK

Word preserves these language settings when exporting to PDF with accessibility tags.

Checking Language Settings

1. Open the Navigation Pane (View > Navigation Pane)
2. Click through different sections
3. Watch the status bar at the bottom for language indication
4. Correct any sections showing incorrect language

PDF Export Verification

1. Go to File > Save As and choose PDF
2. Click Options
3. Ensure Document structure tags for accessibility is checked
4. Save and verify the PDF language is correct in Acrobat

Common Language Codes

Use the most specific code when possible (e.g., en-US rather than just en).

Testing Your Fix

Automated Testing

Adobe Acrobat:

1. Go to Tools > Accessibility > Accessibility Check
2. Run the full check with PDF/UA selected
3. Review any language-related issues

PAC (PDF Accessibility Checker):

1. Open the PDF in PAC
2. Run the PDF/UA check
3. Check Checkpoint 11 results
4. Review all seven failure conditions

Screen Reader Testing

This is the most important test for language:

1. Open the PDF with a screen reader (NVDA, JAWS, VoiceOver)
2. Listen to the entire document being read
3. Pay attention to:
   • Does the pronunciation sound correct for the language?
   • When language changes, does pronunciation change?
   • Are foreign words or names pronounced reasonably?

What to listen for:

• English text read with French accent = wrong language tag
• French text read with English pronunciation = missing language change marker
• Gibberish pronunciation = missing or incorrect language

Manual Verification

1. Open File > Properties > Advanced and verify Language is set
2. Open the Tags panel and check language attributes on key elements
3. For multilingual documents, verify each language section has correct tags

Validation Checklist

• Document has primary language specified in properties
• All content inherits or specifies appropriate language
• Language changes within the document are properly tagged
• Alternative text has appropriate language settings
• Form field tooltips have language specified
• Bookmarks have language specified or inherit correctly
• Screen reader pronunciation sounds correct throughout

Additional Resources

Official Standards and Guidelines

• W3C WCAG 2.1 Success Criterion 3.1.1: Language of Page
• W3C WCAG 2.1 Success Criterion 3.1.2: Language of Parts
• PDF Association Matterhorn Protocol 1.02

Language Code References

• IETF Language Tags (BCP 47)
• Language Subtag Registry
• W3C Language Tags

Tools

• PAC (PDF Accessibility Checker) - Free PDF/UA validation
• NVDA Screen Reader - Free screen reader for testing
• Adobe Acrobat Accessibility Checker

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.