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Links are not tagged or have no description

A link in a PDF consists of visible text and a separate link annotation that makes the area clickable. PDF/UA requires both to sit together in a Link structure element, and the annotation needs a description in its /Contents entry. A PDF/UA check reports rule 7.18.5-1 when the tag is missing and 7.18.5-2 when the description is missing.

Updated

Messages you may see

  • PDF/UA-1 (ISO 14289-1) rule 7.18.5-1: A Link annotation is an Artifact or is nested within … tag (standard type = …) instead of Link
  • PDF/UA-1 (ISO 14289-1) rule 7.18.5-2: A link annotation does not include an alternate description in the Contents key
  • PDF/UA-2 (ISO 14289-2) rule 8.2.5.20-1: A Link annotation is nested within … tag (standard type = …) instead of Link or Reference
  • PDF/UA-2 (ISO 14289-2) rule 8.2.5.20-2: Struct element … contains Link annotations … and … that target different locations (… and … respectively)
  • PDF/UA-2 (ISO 14289-2) rule 8.8-1: Destination in Outline item, OpenAction or Link annotation is not a structure destination

What the rule requires

ISO 14289-1 (PDF/UA-1), clause 7.18.5, contains two requirements, which automated checkers test as separate rules. The Matterhorn Protocol 1.1 lists both under checkpoint 28 (Annotations).

Machine-checkable link rules of PDF/UA-1
RuleRequirement
7.18.5-1Links are tagged as described for the Link element in ISO 32000-1, 14.8.4.4.2: a Link structure element contains the link annotation as an object reference (OBJR) and, as a rule, the link text.
7.18.5-2Each link annotation has an alternate description in its /Contents key (ISO 32000-1, 14.9.3).

Hidden link annotations and link annotations completely outside the crop box are exempt. PDF/UA-2 (ISO 14289-2) changes the details: a link annotation used as real content may sit in a Link or a Reference element (8.2.5.20-1), links that lead to different targets need separate elements (8.2.5.20-2), and links within the same document must use structure destinations, which point to a structure element instead of a page position (8.8). Our checker lists rule 8.8 under Matterhorn checkpoint 27 (Navigation).

Whether the link text and the description make sense is not machine-checkable. A /Contents entry "link" satisfies rule 7.18.5-2 but helps nobody.

Why it matters

Screen readers announce links as links and can list all links of a document so that users can jump directly to one. A link annotation without a Link element is not connected to its text: the screen reader reads the words as normal text and the link is either missing from the list or appears there without a name.

The description in /Contents is what assistive technology can announce for the link itself. Adobe gives the example of a screen reader saying "go to the Acrobat accessibility page" instead of reading out a long URL. The W3C technique PDF11 describes the combination of Link annotation and Link element as the way to meet WCAG success criterion 2.4.4 Link Purpose in PDF.

Common causes

  • Links were added in Acrobat (Edit > Link > Add or edit a link) after the document had been tagged. Adobe notes that items such as comments, links and annotations do not always appear in the Tags tree.
  • Microsoft documents that Word exports header and footer content as artifacts without tags. A hyperlink in a header or footer therefore becomes a link annotation without a Link element.
  • The PDF was exported without tags, or with a converter that creates link annotations but no structure.
  • Hyperlinks in InDesign have no alternate text, or the PDF was exported without the Hyperlinks option.
  • Viewers or tools converted plain URLs in the text into links after the fact.
  • Several files were merged and the links of one file lost their structure.

Example

A link to an annual report. In the failing version the annotation has no structure parent and no /Contents:

31 0 obj
<< /Type /Annot /Subtype /Link
   /Rect [72 700 260 714] /Border [0 0 0]
   /A << /S /URI /URI (https://www.example.org/annual-report-2025.pdf) >> >>
endobj
Failing: link annotation without Link element and without description

In the corrected version the Link element contains the marked text (MCID 7 on the page) and the object reference to the annotation; the annotation has a description and points back with /StructParent:

% content stream of page 5: the visible link text is marked content 7
/Link << /MCID 7 >> BDC
  BT /F1 11 Tf 72 703 Td (Annual report 2025) Tj ET
EMC

40 0 obj
<< /Type /StructElem /S /Link /P 39 0 R /Pg 5 0 R
   /K [ 7 << /Type /OBJR /Obj 31 0 R /Pg 5 0 R >> ] >>
endobj

31 0 obj
<< /Type /Annot /Subtype /Link
   /Rect [72 700 260 714] /Border [0 0 0]
   /A << /S /URI /URI (https://www.example.org/annual-report-2025.pdf) >>
   /Contents (Annual report 2025, PDF document)
   /StructParent 4 >>
endobj
Passing the machine check: Link element with text, OBJR and /Contents

How to fix it

Microsoft Word

Microsoft documents that Word tags hyperlinks on text as Link elements with an object reference (Link – OBJR) when the PDF is exported with structure tags.

  1. Insert links with Insert > Link. Use link text that names the target, such as "Annual report 2025 (PDF)", instead of "click here" or a bare URL.
  2. Move links that matter out of headers and footers into the body text, because Word does not tag header and footer content.
  3. Choose File > Save As or File > Save a Copy, select PDF, then Options, keep Document structure tags for accessibility selected and save.
  4. Check the new PDF. If rule 7.18.5-2 still reports missing descriptions, add them in Acrobat Pro as described below.

Adobe InDesign

  1. Select the text or frame and choose Type > Hyperlinks & Cross-References > New Hyperlink.
  2. Choose the target under Link To and, on the Accessibility tab of the dialog, enter alternate text that describes the target.
  3. Export with File > Export > Adobe PDF (Print) with Create Tagged PDF and Hyperlinks switched on, or with Adobe PDF (Interactive) and Create Tagged PDF.
  4. Check the exported file. If rule 7.18.5-2 remains for some links, add the description in Acrobat Pro.

Adobe's description of the Hyperlinks export option says it preserves hyperlinks and cross-references. Cross-references are links too and need the same check.

Adobe Acrobat Pro

Tag untagged links

  1. Open the Tags panel: menu (Windows) or View (macOS) > Show/Hide > Side panels > Accessibility tags.
  2. Choose Find from the Options menu and search for unmarked links. Adobe describes Find as a search for untagged content, comments, links and annotations, with an option to add tags to the items found.
  3. Tag each link found with the type Link.
  4. Make sure the Link tag contains both the link text and the link object. If the text sits in a separate tag, drag it into the Link tag.

Add descriptions

  • Adobe documents alternate text on the Link tag: select the tag, choose Properties from the Options menu and type the text on the Tag tab of the Touch Up Properties dialog.
  • Rule 7.18.5-2 looks at the /Contents entry of the link annotation, not at the tag. Users report a Preflight fixup in Acrobat Pro that writes this entry for link annotations; check whether your version offers it and review the texts it creates.
  • Run All tools > Prepare for accessibility > Check for accessibility, then check the file here again.

When you create new links in Acrobat, Adobe recommends the Create Link command, which according to Adobe adds the parts that screen readers need to recognise a link.

Check your PDF

Upload the fixed file to see which machine-checkable criteria it meets now. The report lists the remaining problems with their pages.

Open the checker

Questions

Acrobat's Navigation links rule passes. Why does the link check fail?
Adobe's Navigation links rule checks for repetitive navigation links (WCAG 2.4.1 Bypass Blocks), not whether links are tagged. Tags and descriptions are tested by the PDF/UA rules on this page.
Is the URL a good description?
It fills the /Contents entry, so the machine check passes. A short description of the target is more useful, because a long URL read out character by character is hard to follow.
What about internal links in PDF/UA-2?
PDF/UA-2 requires structure destinations for targets within the same document. InDesign's compatibility settings end at PDF 1.7 and Word's PDF options have no version setting, so this rule mainly concerns files from software that produces PDF 2.0.

Sources

  1. ISO 14289-1:2014 – Document management applications – Electronic document file format enhancement for accessibility – Part 1: Use of ISO 32000-1 (PDF/UA-1) – International Organization for Standardization (ISO). Checked on 7 November 2026.
  2. ISO 14289-2:2024 – Document management applications – Electronic document file format enhancement for accessibility – Part 2: Use of ISO 32000-2 (PDF/UA-2) – International Organization for Standardization (ISO), 13 March 2024. Checked on 7 November 2026.
  3. The Matterhorn Protocol 1.1 – PDF Association. Checked on 7 November 2026.
  4. PDF11: Providing links and link text using the Link annotation and the /Link structure element in PDF documents – World Wide Web Consortium (W3C), Web Accessibility Initiative. Checked on 7 November 2026.
  5. Create and verify PDF accessibility (Acrobat Pro) – Adobe (helpx.adobe.com). Checked on 7 November 2026.
  6. Edit document structure with the Content and Tags panels (Acrobat Pro) – Adobe (helpx.adobe.com). Checked on 7 November 2026.
  7. Add links to PDFs – Adobe (helpx.adobe.com), 23 September 2025. Checked on 7 November 2026.
  8. Word PDF Accessibility – Microsoft Learn, 12 May 2026. Checked on 8 November 2026.
  9. Create accessible PDFs – Microsoft Support. Checked on 8 November 2026.
  10. Create hyperlinks (InDesign) – Adobe (helpx.adobe.com), 2 June 2026. Checked on 7 November 2026.
  11. Adobe PDF export options in InDesign – Adobe (helpx.adobe.com), 2 June 2026. Checked on 7 November 2026.