Structural Tagging Integrity

What this test checks

This test checks for structural tagging errors in the PDF document.

Note that this test is experimental and is marked with an Ⓔ in the result title.

Why this maybe a barrier

This test checks for some common structural tagging mistakes in PDF documents namely,

1. Artifacts tagged as real content.
2. Real content marked as artifacts.
3. Improper nesting of artifacts and tagged content.
4. Content not marked as either artifact or real content.

Screen readers rely on a correct distinction between real content and artifacts. Mistagged or untagged content can cause major reading-order failures, skipped content, or misinterpreted elements.

WCAG 2.2 Reference

N.A (PDF/UA-only check).

PDF/UA Principle

Section 7.1: General — "All real content shall be tagged as defined in ISO 32000-1:2008, 14.8. Artifacts (ISO 32000-1:2008, 14.8.2.2.2) shall not be tagged in the structure tree. Content shall be marked in the structure tree with semantically appropriate tags in a logical reading order. Content that does not render and does not have a rendered equivalent shall be marked as an artifact."

For implementation, the test uses the following Matterhorn protocol checkpoints namely:

1. 01-001 — Artifact is tagged as real content.
2. 01-002 — Real content is marked as artifact.
3. 01-003 — Content marked as Artifact is present inside tagged content.
4. 01-004 — Tagged content is present inside content marked as Artifact.
5. 01-005 — Content is neither marked as Artifact nor tagged as real content.