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Well-Tagged PDF (WTPDF)

Using Tagged PDF for Accessibility and Reuse in PDF 2.0

The primary purpose of this specification is to define how to represent electronic documents in PDF 2.0 files in a manner that allows the file to be reusable and accessible across a wide spectrum of possible use-cases.

There is a large overlap between the requirements for reuse and accessibility. However, some requirements are critical for reuse whereas others are critical for accessibility. This document clearly identifies the requirements for each use-case via a conformance level mechanism.

WTPDF identifies the components that shall, should or may be used in these contexts, as well as restrictions on their use. It includes a conformance level mechanism to empower software and document authors to target these use cases.

The specification is fully compatible with ISO 14289-2 (PDF/UA-2), so a file that conforms to the accessibility conformance level defined in this specification also conforms to the latest ISO standard for accessible PDF, and may be marked as such.

Both this document and PDF/UA-2 provide numerous improvements on PDF/UA-1, including:

• comprehensive requirements for the new structure element types introduced in PDF 2.0
• comprehensive requirements for structure element attributes;
• comprehensive requirements for the use of annotations;
• rules governing the inclusion of structure elements defined in PDF 1.7 as well as PDF 2.0;
• detailed requirements for math, including support for MathML;
• requirements for the use of the new Artifact structure element;
• requirements for intra-document links leveraging the structure destinations feature introduced in PDF 2.0;
• the use of PDF 2.0’s Associated Files feature to facilitate the integration of non-PDF content;
• examples of semantically-significant attribute usage.

“If you support WTPDF you also support PDF/UA-2.”

NOTE: We intended version 1.0.0 of this document to be a high-quality PDF/UA-1 file. With new capabilities such as the Arlington PDF Model, we have identified minor deviations from specification caused by various vendor tools. We are working closely with vendors to address these issues, and will issue a dot release once the tooling is corrected.

Comments?

Technical questions about WTPDF are most effectively addressed in the PDF Association’s official pdf-issues GitHub repo.

WTPDF examples

The PDF Association invites its members to contribute example PDF files demonstrating conformance to WTPDF.  To be included such files must be:

• Valid PDF 2.0 (a clean report from the Arlington PDF Model is required);
• Valid PDF/UA-2 (and PDF/A-4 and/or PDF/X-6, for bonus points :-);
• Valid WTPDF (that is, conform to at least one WTPDF conformance level).

Additional PDF Declarations, such as Validated as conforming to PDF/UA-2 or Validated as WTPDF, conformance level accessibility, if applicable.

Note: The PDF Association does not endorse these developers’ representations but presents the examples “as is”.

PDF Association Member	Example(s)
BFO (Big Faceless Organization)	BFO-WTPDF-&-PDFua2.pdf
LaTeX Project	Examples of various types of content

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Download WTPDF

PDF/UA WTPDF