# PDF Logical Structure Tree WCAG Role Mapping Validator Audit a tagged PDF's logical structure tree against PDF/UA-1 (ISO 14289-1) semantics: RoleMap termination, H1-H6 heading hierarchy, Alt text on Figure/Formula, RFC 3066 language tags, illegal nesting, and structure-vs-content MCID reading order — each finding labeled with its Matterhorn Protocol checkpoint. > Canonical page: https://elysiatools.com/en/tools/pdf-logical-structure-tree-validator - **Category:** PDF Tools - **Keywords:** pdf ua, structure tree, rolemap, wcag pdf, matterhorn protocol, tagged pdf, mcid, reading order ## Overview The audit parses per-page structure trees through pdf.js, walks heading/alt/lang/nesting rules from ISO 14289-1 and ISO 32000-1, and compares structure traversal MCID order with content-stream BDC/EMC order. pdf.js 3.x exposes /Alt but not /ActualText and prunes subtrees without marked content on the page — both caveats appear in the report. Heuristic audit; formal PDF/UA certification needs veraPDF or Acrobat. ## Inputs - **PDF file** (file) - **Max pages** (number): Cap on how many pages are audited (large documents). - **Check reading order** (checkbox): Compare structure traversal order with content-stream MCID order (09-001). ## When to use - Check whether a tagged PDF contains a valid logical structure tree. - Review heading levels, Figure and Formula alternative text, language tags, and structural nesting. - Investigate differences between structure traversal order and content-stream MCID order. ## How it works - Upload a PDF file and optionally set the maximum number of pages to audit. - The validator parses per-page structure trees and checks PDF/UA-1 and ISO 32000-1 rules. - It reviews RoleMap termination, H1-H6 hierarchy, Alt text, language tags, and illegal nesting. - When enabled, it compares structure traversal MCIDs with BDC/EMC content-stream order and returns an HTML report. ## Use cases - Accessibility teams can review tagged reports for missing structure, heading-level errors, and absent alternative text. - PDF developers can locate RoleMap, language, nesting, and MCID reading-order findings before revising document generation workflows. - Document reviewers can audit multilingual PDFs and confirm whether declared language tags and structural headings are detectable. ## Frequently asked questions ### What type of file can I upload? Upload one PDF file. The file must use the PDF format. ### Can this validator check an untagged PDF? Yes. It identifies PDFs without a structure tree and reports an untagged-PDF critical finding. ### What does the maximum pages option do? It limits how many pages are audited. The value can range from 1 to 500, with a default of 100. ### What does the reading-order check compare? It compares structure traversal order with the order of MCIDs in the content stream. ### Does this provide formal PDF/UA certification? 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