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Re: Untagged PDF doc with table structure

for

From: Chagnon | PubCom
Date: Feb 18, 2015 11:17AM

Lynn wrote: " in PDF docs, what's the difference between tags and structure?
"

This is one of the toughest concepts we teachers have to explain! I'd love
to hear how others describe it. Here's my take:

Tags are labels. Code labels, specifically, that are read by Assistive
Technologies and are not usually visible to sighted users unless they have
Acrobat Pro. They let AT users know what's a heading 2, a list of bullets,
tables, and other parts of the documents. Tags also do a lot of work for us,
such as assisting us in creating bookmarks and tables of contents, creating
navigation systems, and holding the Alt-text on graphics (Alt-Text is an
attribute on the figure tag and doesn't stand alone on its own).

Structure is the sequence of how the document's pieces will be read, or in
other words, the sequence in which the tagged items are read. Call it
reading order or tag reading order. The structure of some documents can also
have nesting qualities, such as all the pieces of a chapter, and all the
chapters in a book.

An example: If Heading 1 designates a chapter title, then all the paragraph,
bullets, tables, and heading 2 items within that chapter will be nested
inside the main heading 1 tag. This allows AT software to figure out,
hopefully, what goes with what; that all the tags nested within Heading 1 is
a chapter.

Structure is created when you have tags (the right tag labels) and a reading
order (a logical reading order). It is possible that a tagged and structured
document might not be fully accessible because the tags aren't accurate
enough or the reading order is out of whack.

Example number 1: In older versions of MS Word, figures would be placed in
very odd places of the reading order when it was exported to a PDF. If
paragraph 1 stated "see figure 5", figure 5 itself might end up at the very
end of the reading order, not near paragraph 1 where it was referenced. A
sighted person sees figure 5 next to the paragraph, but a screen reader user
doesn't hear it voiced until the last page, and maybe that's page 360 of a
long government document. So the document is tagged and structured, but it's
a faulty structure because the reading order is incorrect.

Example number 2: Graphic designers who use desktop publishing programs like
Adobe InDesign and QuarkXpress create very complex visual layouts. Visually,
things aren't designed in a traditional top down left right pattern but
instead could be scattered all over the physical page. Here's an example of
a 2-page magazine spread:
http://fc02.deviantart.net/fs71/i/2010/082/e/c/Magazine_Layout_Design_1_by_B
reakTheRecords.jpg (This is just a random sample I pulled up on the
Internet, so it is only a graphic of a 2-page spread, no live text or
Alt-text.)

Note that article title (or heading 1) appears on page 2, and the body text
of the story starts on page 1. Backwards! And then there are 2 quotes at the
top of page 1, so obviously the designer wants us to read those at the
beginning of the story, also. And here's a similar example:
https://m1.behance.net/rendition/modules/12455236/disp/322ee0c042b2949607393
d8b1f24ad96.jpg

Whew! Getting a tagged, logical reading order from this type of publication
isn't easy!

Summary:
Structure equals tagged content placed in a logical reading order.

Well, that's my attempt. Would love to hear how others describe the
concepts.

--Bevi Chagnon

-----Original Message-----
From: <EMAIL REMOVED>
[mailto: <EMAIL REMOVED> ] On Behalf Of Lynn Holdsworth
Sent: Wednesday, February 18, 2015 12:11 PM
To: WebAIM Discussion List
Subject: Re: [WebAIM] Untagged PDF doc with table structure

Thanks so much everyone for weighing in - I've found this a very useful
thread indeed.

One more question: in PDF docs, what's the difference between tags and
structure? Ryan mentioned that the doc may include structure but not be
tagged, and I don't understand the difference.

And thanks Duff for the LinkedIn group suggestions. I'll join at least the
first one.

Really hoping that Adobe is working on ironing out the accessibility
glitches in the DownLoad Assistant, as I'd appreciate the chance to learn
about and use what seems like a great bunch of accessibility features in
Acrobat.

Best, Lynn

On 18/02/2015, Andrew Kirkpatrick < <EMAIL REMOVED> > wrote:
> Bim,
> I was talking about both Acrobat and Reader in my reply, sorry if that
> wasn't clear. It is the same process for both.
> AWK
>
> -----Original Message-----
> From: <EMAIL REMOVED>
> [mailto: <EMAIL REMOVED> ] On Behalf Of Bim Egan
> Sent: Wednesday, February 18, 2015 7:13 AM
> To: 'WebAIM Discussion List'
> Subject: Re: [WebAIM] Untagged PDF doc with table structure
>
> Lynn didn't seem to be talking about using Acrobat though. She
> described the experience of many screen reader users in finding a
> table in an untagged
> PDF when opened in Reader, and she asked why this could happen. Her
> message said that the Acrobat installation wasn't accessible.
>
> Bim
>
> -----Original Message-----
> From: <EMAIL REMOVED>
> [mailto: <EMAIL REMOVED> ] On Behalf Of Andrew
> Kirkpatrick
> Sent: 18 February 2015 14:36
> To: WebAIM Discussion List
> Subject: Re: [WebAIM] Untagged PDF doc with table structure
>
> Jon is correct. When Acrobat opens an untagged document and there is
> a client that is using the accessibility API data running, Acrobat (or
> Reader) will add tags to the document. The result is the same as if
> an author used the "add tags" feature in Acrobat. You get Acrobat's
> best interpretation of what the tags should be. That will sometimes
> result in headings, well-formed tables, lists, and other structures.
> Authors who use this feature in Acrobat know that you generally need to
fix some of the tags.
>
>
>
> The result is that the document is tagged temporarily and assistive
> technologies recognize and use the information.
>
>
>
> The dialogs that you see when opening PDF documents give you some
> information about what is going on. To understand better, here's my
> explanation.
>
>
>
> In acrobat or Reader preferences there is a "Reading" category. There
> is a checkbox that is labeled "Confirm before tagging documents". If
> this is checked, then every time that Reader intends to tag an
> untagged document the "Reading an untagged document with assistive
> technology" dialog pops up and the user needs to confirm that this is
> what they'd like to do. If the user selects cancel then the document
> won't be tagged and the reading experience will be essentially
non-existent.
>
>
>
> If you elect to allow the tagging, there are other options as
> mentioned in one of the replies. I recommend using the "infer reading
> order from document" option.
>
>
>
> There are other settings related to large documents and auto-tagging.
> Autotagging takes time, so if you open a very dense 600 page manual
> you may find that Reader takes a long time to do the tagging. It can,
> and we are always looking to improve the efficiency of this process.
> The option for the user is to indicate whether the autotagging should
> occur only on visible pages, on all pages in the document, or on all
> pages except if the document is "large". The user gets to define what
> large means - a user might find that their system is slow at this so
> sets the limit at 25 pages, or might set it higher if their system
> handles this process quickly. The down side of only tagging a few
> pages at a time is that if there are recognized structures on pages
> that haven't been tagged yet (e.g. a heading on page 51) the user
> can't use screen reader heading navigation to jump to it because the tags
don't exist until the page is in view in the reader.
>
>
>
> Hope this helps,
>
> AWK
>
>
>
> -----Original Message-----
> From: <EMAIL REMOVED>
> [mailto: <EMAIL REMOVED> ] On Behalf Of Lynn
> Holdsworth
> Sent: Wednesday, February 18, 2015 4:36 AM
> To: WebAIM Discussion List
> Subject: [WebAIM] Untagged PDF doc with table structure
>
>
>
> Hi all,
>
>
>
> Apologies if PDF accessibility is off topic. If so is there a list
> that covers this?
>
>
>
> But if not ...
>
>
>
> I open a PDF document, and Adobe Reader alerts me that it's untagged.
>
>
>
> So I begin to peruse it using JAWS, and come across a table whose
> structure is robust enough for me to move around it using the JAWS table
keystrokes.
>
>
>
> Does this mean there *are* tags in the document after all? Or has
> Adobe Reader used heuristics to add tags to improve the doc's
> accessibility, since my settings flag up that I'm using a screenreader?
>
>
>
> I tried to download a trial version of Acrobat Pro so as to examine
> the document structure, but the download assistant seems inaccessible.
>
>
>
> Thanks as always, Lynn
>
> >
> > list messages to
> <EMAIL REMOVED> <mailto: <EMAIL REMOVED> >
> > > list messages to <EMAIL REMOVED>
>
> > > list messages to <EMAIL REMOVED>
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messages to <EMAIL REMOVED>