PDF Accessibility Techniques – Example PASS & FAIL

As a preview of the soon-to-be-published Fundamental Techniques the following techniques represent examples of the PDF Accessibility LWG's ongoing work.

The PASS example conforms to ISO 14289-1 (PDF/UA-1).

Graphics representing text correctly tagged

Pass / Fail: PASS

Description

The objective of this technique is to show how to tag non-text content that is intended to be consumed as text. In this example, graphics were used to place the word "paragraph" on the page, instead of text objects. To make the characters of this graphic extractable, ActualText on a separate Span tag is used. The ActualText matches the visual appearance of the related graphics.

Note: The Span tag is always the recommended choice if ActualText is required because ActualText removes the semantics of tags. In spite of the previous statement, ActualText may also work when the tag is one of the following: Lbl (outside of List structures), P, BibEntry, BlockQuote, Caption, Code, Note, Quote. However, ActualText should never be assigned to other tags.

Note: This passes PDF/UA requirements but not WCAG 1.4.5. Images of text are not allowed in WCAG.

Example file

UA_Tpdf-0160-F2-Image-representing-text

Test

Procedure

1. Check that the related characters are present as extractable characters for content intended to be consumed as text.
2. Check that Unicode can be derived for any text content.
3. Check that the extractable characters match their visual appearance.
4. Check that the Natural Language is set for any text content.

Expected Results

Checks #1 through #4 are all true.

Applicable WCAG 2.2 Success Criteria

1.1.1, 1.3.1, 1.4.5, 3.1.1, 3.1.2

Applicable Matterhorn Protocol checkpoints

01-006, 08-001, 08-002, 10-001, 11-001, 11-002, 11-006, 13-001, 13-004, 13-005, 13-008

Technique finder: UA_Tpdf-F2_07

Graphics representing text incorrectly tagged as figure

Pass/Fail: FAIL

Description

This example demonstrates the failure condition that applies for non-text content that is intended to be consumed as text, but appropriate ActualText is missing. In this example, graphics were used to place the word "paragraph" on the page, instead of text objects. In this case the related non-text content is incorrectly tagged as a Figure with alt text.

Example file

UA_Tpdf-0227-F2-Image-representing-text-Fail

Test

Procedure

1. Check that the related characters are present as extractable characters for content intended to be consumed as text.
2. Check that Unicode can be derived for any text content.
3. Check that the extractable characters match their visual appearance.
4. Check that the Natural Language is set for any text content.

Expected Results

Although checks #2 and #4 are true, checks #1 and 3 are false.

Applicable WCAG 2.2 Success Criteria

1.1.1, 1.3.1, 1.4.5, 3.1.1, 3.1.2

Applicable Matterhorn Protocol

01-006, 08-001, 08-002, 10-001, 11-001, 11-002, 11-006, 13-001, 13-004, 13-005, 13-008

Technique finder: UA_Tpdf-F2_08