Non-standard structure type is remapped

Non-standard structure type is remapped is a PDF/UA check in PAC, the free PDF Accessibility Checker. It fails when a PDF's hidden structure uses a custom tag name, such as Para or Heading1, without mapping it to a standard tag like P or H1. The mapping lives in the PDF's role map, and PDF/UA, the ISO standard for accessible PDFs, requires every custom tag to lead to exactly one standard tag.

What this means

The PDF specification defines a fixed set of standard structure types, the tag names assistive technology understands: Document, Sect, P, H1 to H6, L, LI, Table, TH, TD, Figure, Link and others. Authoring tools often add tags of their own, usually named after styles in the source document. The role map translates each custom name into a standard one, for example BodyText means P and Head1 means H1.

People often search for this message with the words "PDF/UA role map". It fails when:

• a custom tag has no role map entry at all;
• a custom tag is mapped to another custom tag that isn't mapped any further, or the mappings loop back on themselves.

A related problem, which PDF/UA also forbids, is remapping a standard tag, such as mapping P to H1 or Figure to Span. Includoc reports broken mappings like these as a separate rule, shown below.

One detail catches people out: tag names are case-sensitive. A lowercase p or h1 isn't the standard tag, even though it looks like it, so it needs a mapping too.

Why it matters

Assistive technology only knows what standard tags mean. An unmapped Head1 may be read as plain text, so the heading disappears from the list of headings that screen reader users navigate by. An unmapped list loses its item count, and an unmapped table can lose its rows and columns. The structure that sighted readers can see isn't available to assistive technology, which fails WCAG 2.1 success criterion 1.3.1, Info and Relationships.

How to fix it in Acrobat Pro and re-check in PAC

Fix it in the source file

Custom tags usually come from styles, so the cleanest fix is in the authoring app:

• InDesign: give every paragraph style a standard PDF tag in its Export Tagging settings: P for body text, H1 to H6 for headings and Artifact for anything that's purely decorative. Edit All Export Tags in the Paragraph Styles panel menu sets them all in one place.
• Word: use the built-in Heading 1, Heading 2 and list styles for structure, rather than custom styles that only look like headings. Then export with Document structure tags for accessibility turned on.
• Other tools: a tool that writes its own tag names should also write a role map. If yours doesn't, tag the document in a tool that does, then check it in PAC.

Fix it automatically with Includoc

Includoc fixes this automatically. We map each custom tag to the closest standard tag, or replace it with a standard tag, and rebuild the role map so every custom name leads to exactly one standard tag, without loops or remapped standard tags.

What you confirm is the result for headings: because custom styles often hide heading levels, check the outline in the headings panel on the review screen and correct any level that came through wrong.

Standards

Related errors

• Appropriate nesting – Failed: once headings are mapped correctly, their levels still have to form a clean outline.
• Content is tagged or artifacted: another core PDF/UA structure check.

For background on tags and role maps, read What is a tagged PDF?, or check a PDF free to see which custom tags your file uses.