W3C home > Mailing lists > Public > w3c-wai-ig@w3.org > July to September 2012

RE: PDF Accessibility Reading Order

From: Jonathan Avila <jon.avila@ssbbartgroup.com>
Date: Tue, 17 Jul 2012 12:39:47 -0400
Message-ID: <b24ab8014afd6b5e00e283a34cf97b04@mail.gmail.com>
To: andrew.nordlund@hrsdc-rhdcc.gc.ca, jason@knowbility.org, w3c-wai-ig@w3.org
Assistive technologies such as screen readers use the logical order of
tags in the tags tree to render content in the proper reading order to
users.  It's an unfortunate misconception that the "order" panel is the
best place to do this as it is not.  From my experience the Order panels
seems to update the tags panel and content panel simultaneously.  Problems
often arise when content blocks span multiple pages.   I primarily work in
the tags tree and try to avoid the order panel if at all possible.
Because uninformed customers check the order panel and assume it is how
the document will be read by assistive technology we strive to ensure that
the order panel reading order matches the tags tree.  I have been able to
succeed with this by manipulating the tags and content panels when the
order panel gets out of sync with the tags panel -- although sometimes the
tags must be deleted to fix the issue.  Work in content panel should not
be done lightly as removing content from this panel will remove it
visually from the document.

I've also found that using some of the features of the touch up reading
order tool to block text seems to fragment the text into small blocks.
While this may not affect reading with screen readers it seems to not be
helpful.  I find that using the combination of selecting text with "edit
original document text" or  "move or change object" combined with the
"create tag from selection" feature produces more appropriate text blocks
in the tag tree structure.   These toolbars also have special mode when
control, shift, or alt are depressed which are very helpful in combining
blocks of content into one tag.

I agree with Jason's other comments on the tab order of links and form
elements.

Best Regards,

Jonathan

-----Original Message-----
From: andrew.nordlund@hrsdc-rhdcc.gc.ca
[mailto:andrew.nordlund@hrsdc-rhdcc.gc.ca]
Sent: Thursday, July 12, 2012 8:02 AM
To: jason@knowbility.org; w3c-wai-ig@w3.org
Subject: RE: PDF Accessibility Reading Order

Hi Jason,

Yes, thank you very much.  It makes sense.  For a11y purposes, you want
the layout of the page to be functionally identical regardless of if
you're reading it as a sighted user, converting the document to text,
reading the whole document at once with a screen reader, reading the
document bit by bit with a screen reader, or tabbing through the form
fields and links.

It's confusing because the Order and the Tags can be ordered differently,
and independently of each other.

Andrew Nordlund


-----Original Message-----
From: Jason Hester [mailto:jason@knowbility.org]
Sent: 2012-07-11 1:19 PM
To: w3c-wai-ig@w3.org
Subject: RE: PDF Accessibility Reading Order

Hi Andrew,

We deal with this issue quite frequently and it is generally the case that
the reading order, and the tag order should match as closely as possible.
They are both equally important to ensure your document reads in the
correct order across screen-readers.

If you are dealing with legacy PDF documents, then tagging each page
element in the order in which it should read is the easiest way to ensure
the tag order and the reading order panels match up.  If you run into an
issue where the order begins to go astray, it is important to immediately
correct the order in either the "order panel or " tags panel" before it
gets out of hand.  Waiting till the page or document is tagged to correct
reading order issues will make it nearly impossible to fix without
deleting all the tags and starting over.

You will notice that all tags of the same type that also appear in
succession in the tags panel are grouped together and assigned a number in
the order panel. If you run into an issue that causes tags that are not in
succession to be grouped together in the order panel, as is sometimes the
case with 2 column text, you must delete those tags and re-tag them in the
order you wish them to read using the "TouchUp Reading Order" tool. While
reflow gives you a quick snapshot of the reading order of your document,
you can also use the touch up reading order tool to view the order of the
grouped tags on the page.  The grey boxes that appear around each section
of tagged text, etc. will have a number in the corner that correlates to
the order in the order panel.

There are 2 different areas of the tab order that you also need to check,
depending on whether you have links, form elements or both.  The tab order
for links will be tied more closely to the tag and reading order panels.
For this you should also check the "page thumbnails" panel, use ctrl + A
to select all pages, right click on a page and under "Tab Order" and
ensure "Use Document Structure" is selected.

If you have forms, the second area you want to check is in the "Form
Editor".  In the form editor under "Tab Order" if you "Order Tabs
Manually"
this will allow you to re-arrange the order of the forms as they appear on
a tab through of the document. *Warning*: re-arranging the tab order of
the forms after the forms have been tagged may cause the form tags to be
deleted, in which case you will need to re-tag them.

PDF accessibility can be confusing, difficult and time consuming in legacy
files, but it sounds like you are on the right track. It is good to see
you are utilizing the PDF draft techniques for WCAG 2.0 from the W3C.
Before this draft was published we found a lot of these techniques and
others through trial and error by testing with persons using assistive
technology.

Hope this information helps.

Cheers,


Jason M. Hester
Production Manager
AccessWorks
Knowbility, inc.
512.305.0201

-----Original Message-----
From: andrew.nordlund@hrsdc-rhdcc.gc.ca
[mailto:andrew.nordlund@hrsdc-rhdcc.gc.ca]
Sent: Wednesday, July 11, 2012 10:20 AM
To: w3c-wai-ig@w3.org
Subject: PDF Accessibility Reading Order

Hi,

	I'm in a position where I have to check several PDFs for
compliance to WCAG 2.0.  I use the PDF Techniques for WCAG 2.0 site
(http://www.w3.org/WAI/GL/WCAG20-TECHS/pdf.html) to check for sufficient
techniques.  These techniques seem to be aimed at people who create PDFs.
I do not create.  I merely check other author's PDFs.  I use Adobe Acrobat
Pro X to check the PDFs.

	But one technique has me quite confused as to what to check.
PDF3:
Ensuring correct tab and reading order in PDF documents.   There are two
parts to that:  1) Tab Order, and 2) Reading Order.

	Tab order is easy.  Tab through the form and see if it goes in
order.

	Reading Order is confusing.

	First, let me say that 99% of the PDFs that come into my inbox do
_not_ allow me to reflow (CTRL+4).  That menu option is greyed out.  So I
use the Order panel and Tag panel.

	If I run NVDA and open up a PDF, NVDA reads the PDF in Tag order.
However, if I select one element, and navigate with my arrow keys, NVDA
follows the order in the Order panel sometimes, and other times the Tag
order.  If I use Adobe's Read Out Loud function and use select "Read to
End
of Document" or "Read this Page Only", it follows he Tag order.   But, if
I
navigate using my keyboard using my arrow keys, it seems to Read Out Loud
in the order in the Order panel.

	If I go File -> Save As... -> More Options -> Text (Accessible),
it gets saved in the Tag order.

	On the W3C site
(http://www.w3.org/WAI/GL/WCAG20-TECHS/pdf.html#PDF3) it seems to imply I
need to check the order in the Order panel.

	If I search the web, other sites and documents have conflicting
information.  Some say it's all about Tag order.  Others just tell you how
to fix the order in the Order panel.

	Again, on the W3C site, I see the following:  "The reading order
of a PDF document is the tag order of document elements, including
interactive elements."
(http://www.w3.org/WAI/GL/WCAG20-TECHS/pdf.html#PDF3-description).  That
seems to imply that the reading order _is_ the Tag Order.  If the reading
order _is_ the Tag order, why is there one panel for reading order, and
another for tag order?  Shouldn't they be the same?

	Everything I've read, all taken together _implies_ the order in
the Order panel should match the Tag order.  I have not seen this
explicitly stated anywhere.


	So, to ensure greater accessibility, should I be checking the
Order panel, the Tag Order, or both?  Do I make sure the order in the
Order panel matches the Tag Order?
	

	Thanks for your help!


	Andrew Nordlund
Received on Tuesday, 17 July 2012 16:40:16 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 5 February 2014 07:13:30 UTC