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RE: PDF Accessibility Reading Order

From: Jason Hester <jason@knowbility.org>
Date: Wed, 11 Jul 2012 12:18:58 -0500
To: <w3c-wai-ig@w3.org>
Message-ID: <002501cd5f89$42da1840$c88e48c0$@knowbility.org>
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. 


Jason M. Hester
Production Manager
Knowbility, inc.

-----Original Message-----
From: 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


	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

	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
(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 Wednesday, 11 July 2012 17:19:34 UTC

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