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Thread: PDF reading order and tag order
Number of posts in this thread: 11 (In chronological order)
From: Alan Zaitchik
Date: Wed, Jun 07 2017 10:18AM
Subject: PDF reading order and tag order
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I am working on a monthly newsletter that has a standard banner (banner
image and title- apart from the date it never changes) followed by 4
'articles'.
I reworked the tags so that they are in the correct order with the correct
semantic structures (I believe).
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!
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>
As always your advice is MOST appreciated!
A
Alan Zaitchik
Center For Social Innovation
200 Reservoir Street, Suite 202
Needham, Massachusetts 02494
www.center4si.com
From: Philip Kiff
Date: Wed, Jun 07 2017 10:56AM
Subject: Re: PDF reading order and tag order
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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.
From: Chagnon | PubCom
Date: Wed, Jun 07 2017 11:07AM
Subject: Re: PDF reading order and tag order
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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 |
- - -
From: Jonathan Avila
Date: Wed, Jun 07 2017 11:46AM
Subject: Re: PDF reading order and tag order
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> 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 ADDRESS REMOVED =
703.637.8957 (Office)
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From: Chagnon | PubCom
Date: Wed, Jun 07 2017 12:10PM
Subject: Re: PDF reading order and tag order
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Yes, good point Jonathan.
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.
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.
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.
--Bevi Chagnon
From: Philip Kiff
Date: Wed, Jun 07 2017 12:30PM
Subject: Re: PDF reading order and tag order
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I didn't mean to underplay the importance of making the reading order
make sense to other assistive technology. I honestly didn't know that
the Content order was used for *any* of them! Thanks for the info.
Like Bevi, I strive to get both to sync up wherever possible, and that
is for sure the best practice.
Phil.
On 2017-06-07 14:10, Chagnon | PubCom wrote:
> Yes, good point Jonathan.
>
> 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.
>
> 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.
>
> 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.
>
> --Bevi Chagnon
>
>
From: Duff Johnson
Date: Wed, Jun 07 2017 12:51PM
Subject: Re: PDF reading order and tag order
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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.
>
From: Alastair Campbell
Date: Mon, Jun 12 2017 5:07AM
Subject: Re: PDF reading order and tag order
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Hi Duff,
On this bit:
> 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.
That came up in a discussion about WCAG 2.1 where we are looking at
increasing the resize-content aspect:
https://github.com/w3c/wcag21/issues/77#issuecomment-306385027
Are there techniques for defining (or at least controlling) the order in
which a PDF document is reflowed?
Cheers,
-Alastair
On Wed, Jun 7, 2017 at 7:51 PM, Duff Johnson < = EMAIL ADDRESS REMOVED = > wrote:
> 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.
>
>
>
> >
From: Duff Johnson
Date: Mon, Jun 12 2017 7:56AM
Subject: Re: PDF reading order and tag order
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Hi Alastair,
> On this bit:
>> 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.
>
> That came up in a discussion about WCAG 2.1 where we are looking at
> increasing the resize-content aspect:
> https://github.com/w3c/wcag21/issues/77#issuecomment-306385027
>
> Are there techniques for defining (or at least controlling) the order in
> which a PDF document is reflowed?
The first thing to say (boring and repetitive as it may be) is this: software that uses tagged PDF does not have *any* ambiguity about ordering, for reflow or any other purpose. This is why support for tagged PDF is *critical* to accessibility. Software that does *not* support tagged PDF is not AT software with respect to PDF files. Period.
Now... that doesn't stop (a) vendors from selling such software, or (b) end-users confusing such software with that which does support tagged PDF.
So... returning to your question...
If we're talking about strategies for dealing with software that does *not* use tagged PDF, then, yes, the Order panel is useful. Use at your peril however, as the process of re-ordering page-content in PDF is fraught with peril, including the dreaded 'z-order error- in which stuff just seems to.... disappear.
Unfortunately, the junky old 'Touch Up Reading Order Tool- in Acrobat Professional edits *both* tags *and* content order at the same time, with no options to do otherwise and no warning of the problems that can result.
Duff.
From: Alastair Campbell
Date: Thu, Jun 15 2017 3:20AM
Subject: Re: PDF reading order and tag order
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Thanks Duff,
I appreciate the user-agent responsibility, but would you consider Acrobat
Reader to fulfil that for reflow?
It appears to follow the settings in the content/order panel rather than
tags for reflow, which is partly why I asked the question in the first
place.
Cheers,
-Alastair
From: Duff Johnson
Date: Thu, Jun 15 2017 7:33AM
Subject: Re: PDF reading order and tag order
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Hi Alastair,
> I appreciate the user-agent responsibility, but would you consider Acrobat
> Reader to fulfil that for reflow?
No.
> It appears to follow the settings in the content/order panel rather than
> tags for reflow, which is partly why I asked the question in the first
> place.
I'm not suggesting that Reflow (in today's Acrobat) isn't useful to some people, some of the time.
However, since it does not use tags to order content or determine semantics it is not AT.
Duff.