WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: PDF reading order and tag order

for

From: Duff Johnson
Date: Jun 7, 2017 12:51PM

A couple of things to be said...

> Add braille printers to the lineup that use the order panel, not the tags. At least that was the case a couple of years ago when some of our clients with visitors centers were printing braille visitor guides.

No-one should be under the impression that there's anything about the "order panel" that's truly about accessibility. For the purposes of this conversation it can be boiled down as follows:

- The 'order panel- in Acrobat Professional denotes the sequence in which objects are painted onto the page. This is fundamentally orthogonal to the question of 'reading order-, which is denoted *entirely* by the use of "tagged PDF-. Often, they align to one degree or another. In most cases, there are significant discontinuities.

- Software either uses or does not use 'tagged PDF-

- Software that does not use tagged PDF (such as the Reflow feature in Adobe Reader, for example) has to guess to infer a reading-order. Leaving such accessibility basics up to software heuristics is manifestly NOT what accessibility is all about.

- As a concession to today's world where many AT software don't 'do- tagged PDF, Bevi's right that aligning content order and tag order to the extent possible creates value for users who are saddled with the aforementioned software.

> Talking with a colleague, it's hard for us to know which technologies use which order and there's no central source of information that covers all of the A.T. on the market today. Plus people might be using older A.T. that could be using the order, not the tags.

There's nothing fixed about this. While current-generation AT software may not used tagged PDF, the next version of that software may do so. But not, of course, if people don't ask for it.

> Our recommendation: try to get both to synch up, but if you have to compromise, make the tags accurate and the order can slide a bit. Not too much, but a bit.

Since the 'order panel- can't accommodate discontinuous content... or even a paragraph that spans two pages, compromise is indeed essential.

It's just as important to educate service bureaus and the like to point out to them that if they are getting their 'reading order- from page-content instead of from tags (when present) they are doing their end-users a disservice.

Trying to design a PDF file to accommodate software that does not use PDF accessibility is something one should consider carefully, and preferably, reject. In my view, it makes more sense to insist on software that actually understands accessible PDF files (contact the vendor!!!) rather than invest in the prodigious amounts of labor required to make PDF files sort-of 'work- with manifestly substandard software.

Duff.



> -----Original Message-----
> From: WebAIM-Forum [mailto: <EMAIL REMOVED> ] On Behalf Of Jonathan Avila
> Sent: Wednesday, June 7, 2017 1:46 PM
> To: WebAIM Discussion List < <EMAIL REMOVED> >
> Subject: Re: [WebAIM] PDF reading order and tag order
>
>> If you were deaf/blind, you'd be using a braille device like a braille keyboard, which most likely would use the Order reading order, not the Tag reading order.
>
> It is my experience that most refreshable Braille displays are driven by screen readers and that most screen readers use the tag order. The content order does appear to be used by a limited number of tools -- in some situations for the read out loud tool but not other means of navigation with read out loud. It also would likely be used via the reflow option. So both orders are important -- but I'd say the tag order is more often used anything that is in the tag order can be repurposed by other tools more easily such as the VIP Reader and thus is the most important if you couldn't synch them up.
>
> Jonathan
>
> Jonathan Avila
> Chief Accessibility Officer
> SSB BART Group (soon to be Level Access) <EMAIL REMOVED>
> 703.637.8957 (Office)
> Visit us online: Website | Twitter | Facebook | LinkedIn | Blog Looking to boost your accessibility knowledge? Check out our free webinars!
>
> The information contained in this transmission may be attorney privileged and/or confidential information intended for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any use, dissemination, distribution or copying of this communication is strictly prohibited.
>
> -----Original Message-----
> From: WebAIM-Forum [mailto: <EMAIL REMOVED> ] On Behalf Of Chagnon | PubCom
> Sent: Wednesday, June 07, 2017 1:07 PM
> To: 'WebAIM Discussion List'
> Subject: Re: [WebAIM] PDF reading order and tag order
>
> Quote: "The most important order in an accessible PDF is the tag order viewable in the Tags pane."
>
> I'd say that "most important" is in the mind of the individual!
>
> If you were deaf/blind, you'd be using a braille device like a braille keyboard, which most likely would use the Order reading order, not the Tag reading order.
>
> Many other A.T. for cognitive, neurologic, and mobility disabilities use the Order, too.
>
> Bottom line: both reading orders are important if you want to provide accessibility to all of your users.
>
> --Bevi Chagnon
>
> - - -
> Bevi Chagnon | www.PubCom.com
> Technologists, Consultants, Trainers, Designers, and Developers for publishing & communication
> | Acrobat PDF | Print | EPUBS | Sec. 508 Accessibility |
> - - -
>
> -----Original Message-----
> From: WebAIM-Forum [mailto: <EMAIL REMOVED> ] On Behalf Of Philip Kiff
> Sent: Wednesday, June 7, 2017 12:57 PM
> To: <EMAIL REMOVED>
> Subject: Re: [WebAIM] PDF reading order and tag order
>
> On 2017-06-07 12:18, Alan Zaitchik wrote:
>> [....]
>> But I have 2 questions.
>> 1. The Acrobat Reading order tool jumps around with little regard (it
>> seems) for my reordering and restructuring the tabs, even though I set
>> my 'Preferences' for reading order to 'Infer from document structure'.
>> Is this bogus? Need I be concerned? When I use the tool to reorder it
>> screws up the tags!
> The Acrobat "Touch Up Reading Order" tool is poorly named and the order shown by the numbers in Acrobat can be misleading until you understand that there is more than one "order" in a PDF.
>
> The most important order in an accessible PDF is the tag order viewable in the Tags pane. The Order pane does not show this order, but instead shows the "Content" order which is based on how the content is actually placed in the file.
>
> Screenreaders use the Tag order. Adobe's built-in Read Aloud feature I think uses the Content order.
>
> To change the Tag order you simply move tags up and down the Tags pane.
> To make the Content order match the Tags order, you can try moving things around in the Order pane or directly in the Content pane itself.
> However, your viewable content and your tags can easily get screwed up if you use the Order pane to move things around, especially if you have any tags nested inside other tags (like Spans or Figures inside P's inside Article's).
>
> The WebAIM site has a pretty good explanation of how to re-order a PDF file here:
> http://webaim.org/techniques/acrobat/acrobat#touchup
>
> I like to think of the Content order as something like the "printing"
> order, because if you start moving these items around you can end up making some items disappear behind others, as though they have been "printed" over by a non-transparent block of text or figure that appears after them in the content order.
>
> If forced to choose, always prioritize getting the tag order right rather than the Order panel order.
>
>> 2. I did indeed create 4 <article> sections but was unsure whether I
>> should group the banner elements in some section or just list them as
>> direct children of <document> ahead of the first <article>. My concern
>> here is to use only well-supported HTML5 tags that will work with JAWS
>> and other screen readers. Is the following structure OK?
>> <Document>
>> <Figure>
>> <H1>
>> <P>
>> <Article>
>> <Article>
>>
>> <Article>
>>
>> <Article>
>>
> Your structure looks okay to me!
>
> Phil.
> > > >
> > > >
> > > >