WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: [WebAim] Whither /TOC and /TOCI in PDF 2.0? PDF accessibility question.


From: chagnon@pubcom.com
Date: May 14, 2019 1:32PM

Speaking as a member of the PDF Association (trade association for the PDF
file format) and a US delegate to the PDF and PDF/UA ISO standards
committees. (Whew! No wonder I'm tired!)

Since these standards are copyrighted by the ISO, please understand that I
can only talk about items that are currently published and not those in

This is a detailed reply about PDF and PDF/UA.

The short summary is at the end: search for "Summary."

Let's clarify all these PDF numbers and standards so you can understand what
they control and who they're intended for.

There's the main PDF standard (ISO 32000) that covers everything about all
kinds of PDF files. PDFs are used for hundreds of different uses - beyond
what we talk about in this forum which are document files that must be
accessible. The world uses engineering PDFs, archival PDFs, legal PDFs,
press-printing PDFs, architectural PDFs, technical drawing PDFs, accounting
PDFs, and any kind of PDF they can dream up. (This is why the PDF file
format isn't going away anytime soon, regardless of whether you like them or

PDF ISO 32000 was originally published as PDF 1.7 and is now at version 2.0
(what Rick referred to as "PDF 2.0"). The technical standard number is ISO
32000-2 which was released in August 2017. It is published by the ISO at

PDF 2.0 doesn't say much about accessibility, other than, if I recall
correctly, a couple of references to the PDF/UA Universal Access standard.

There are several related PDF sub-sets of the main standard for specific
types of PDFs.

For us in accessibility, we use PDF/UA - Universal Access (ISO 14289
https://www.iso.org/standard/64599.html) which defines what is needed to
make a PDF that conforms to the PDF/UA standard and can be accessed by
various computer technologies, including (but not limited to) assistive

There are other PDF standards like those for PDF/A (archival documents),
PDF/E (engineering documents), PDF/X (printing and graphics exchange
documents) and more. You can learn about these different standards at the
PDF Association's website, https://www.pdfa.org/resource/

Today's ISO's standards are not written for us who create content, remediate
PDFs, or export PDFs from MS Office and other programs. Instead, the
standards provide software engineers the programming details they need to
program their software to create standards-conforming PDFs. Some companies:
Adobe, Microsoft, Nuance, FoxIt, Oracle, Quicken, Intuit, iText, Axes4, and
other PDF-generating software companies.

For us, the standards as written are hard to interpret and put into
practice. The PDF Association has some helpful resources about putting the
various standards into practice. And then you have everyone's reading of the
ISO tea leaves, and their interpretation and application of the standards,
including my own, Karen McCall's, and HHS's.


PDF 2.0 = ISO 32000-2 released in August 2017.
It is only now beginning to be deployed by software manufacturers, and I
don't know of any assistive technology manufacturers who are deploying it at
this time because it doesn't define accessibility at all. It's a global
standard for all PDFs, not specifically for accessible PDFs.
Don't even look PDF 2.0. It's not what you need.

PDF/UA = ISO 14289 for Universal Access, released in 2014.
Version 1 PDF/UA-1 is the current standard that describes how to make
accessible PDFs (remember, it's from a programmer's viewpoint but there is
some substance for content creators and remediators).

PDF/UA-2 (version 2) is in development and not yet released by the ISO. It
will be a while before it's completed, accepted by the ISO, published by the
ISO, and then formally adopted by the Access Board under Sec. 508. It will
take a few years for all these steps to be completed.

Sec. 508 regulation states WCAG 2.0 and PDF/UA-1 are the appropriate
standards for accessible U S Federal I C T. It takes a while for the Access
Board to go through the formal federal process of updating
regulations...years most likely! So the accessibility community will be
working with WCAG 2.0 and PDF/UA-1 for the foreseeable future.

Don't worry about PDF 2.0 & PDF/UA-2.
They are not in play at this time, and they are not required by Sec. 508.
Follow the current PDF 1.7 & PDF/UA-1, not PDF/UA-2.

Rick, your questions (excellent questions!) are being addressed by the
committee. And that's all I can say.
PDF 2.0 and PDF/UA-2 are very different in their approach to PDFs and
accessibility. It's the foundation for the PDF of the future. The committees
are aware that there needs to be a smooth transition from PDF 1.7 & PDF/UA-1
and PDF 2.0 & PDF/UA-2.

Rick wrote: "Or maybe PDF 2.0 is ignoreable for, say, the next ten years in
terms of accessibility, & most other things??"
Yes! But sooner than 10 years. My crystal ball says 5 years for
accessibility, and sooner for other advanced PDF technologies.

Most likely we'll see a slow phase-in throughout our industry, starting with
Adobe and Microsoft giving us new tools to create documents to the new
standards, new utilities that convert PDFs to the new standards, new
checkers that check to the new standards, and new A T that can work with
PDFs made to both the current PDF/UA-1 and future PDF/UA-2 standards.

Hope this helps!


- - -
Bevi Chagnon, founder/CEO | <EMAIL REMOVED>
- - -
PubCom: Technologists for Accessible Design + Publishing
consulting . training . development . design . sec. 508 services
Upcoming classes at www.PubCom.com/classes
- - -
Latest blog-newsletter - Accessibility Tips at www.PubCom.com/blog

-----Original Message-----
From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of Rick
Sent: Tuesday, May 14, 2019 1:38 PM
To: WebAIM Discussion List < <EMAIL REMOVED> >
Subject: [WebAIM] [WebAim] Whither /TOC and /TOCI in PDF 2.0? PDF
accessibility question.

Hello Everyone,

This is a question about accessibility and the PDF 2.0 standard.

The PDF 2.0 standard, ISO 32000-2:2017(E), says that /TOC and /TOCI, and
several other standard structure elements, are no longer 'defined'. (Annex
M, page 958.)

OTOH there are many US Goverment agency documents containing accessibility
guidelines saying, e.g., entries in tables of contents *must* be tagged
(Table of contents entries in the PDF version of ISO 32000-2:2017(E) are
tagged /TOCI. That's presumably because it's a PDF 1.7 document.)

The complete list of previously-defined standard structure elements,
*undefined* by PDF 2.0, is: Sect, Art, BlockQuote, TOC, TOCI, Index,
NonStruct, Private, Quote, Note, Reference, BibEntry, Code.

Does anyone know why these standard structure elements were 'undefined' in
PDF 2.0?
What is the significance of their removal/undefining/defenestration in PDF
And what should be used instead?

If the PDF version of ISO 32000-2:2017(E) PDF 2.0 standard were to be in
Version 2.0 PDF instead of version 1.7 PDF, would the table the table of
contents entries still be tagged /TOCI, or tagged some other way?

The answers must be obvious, but I can't find 'em. If anyone has time to
explain this, it would be wonderful, especially if the explanation could be
made at a level suitable for someone who finds understanding the various ISO
PDF standards woefully difficult.

Or maybe PDF 2.0 is ignoreable for, say, the next ten years in terms of
accessibility, & most other things??

Thanks very much ...