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Re: PDFs and NVDA

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From: Bevi Chagnon
Date: Aug 21, 2011 2:57PM

Lisa, I think you mean "headings" not "headers."
They are very different parts of a page.
To help understand the difference: when you think of a header also think of
its mate, a footer. Headers are running headers (aka page numbers, folios,
repeating info) that repeat at the top of every page.

A heading is a headline, subhead, title or something similar that is part of
the body text on a page. Headings are used by assistive technologies for
quick navigation while headers are usually ignored.

Similar usage for tables. A table header is the repeating information at the
top and includes the column heads. A table heading falls in within the body
of the table and acts like a subhead, dividing one portion of a table from
another.
In tables, the header is used by assistive technologies to orientate the
user, while table headings (subheads) are usually read like any other text
in the table and often confuse the heck out of AT users.

--Bevi Chagnon
(former editor and typesetting)

--
Bevi Chagnon | <EMAIL REMOVED>
PubCom - Trainers, consultants, designers, and developers
Print, Web, Acrobat, XML, eBooks, and Federal Section 508
--
* It's our 30th Year! *


-----Original Message-----
From: <EMAIL REMOVED>
[mailto: <EMAIL REMOVED> ] On Behalf Of LSnider
Sent: Sunday, August 21, 2011 3:24 PM
To: WebAIM Discussion List
Subject: Re: [WebAIM] PDFs and NVDA

Hi Duff,

Thanks for your answers, much appreciated. So a few follow up questions:

-If most people use the tagged reading order, what are the uses for the
other reading orders in Acrobat/Reader?

-If I don't use proper headers in a Word doc (which will be made into the
PDF), the tagging can't tell what is a header, correct? It just guesses? To
me with my testing, it seems like it guesses and I think that is what you
said below, but just wanted to confirm.

-The touchup reading order in Acrobat can be used to tweak what the tagging
does? I haven't used that one a lot before...I usually try to make well
structured documents in Word and they usually come out okay, but maybe I
should be using that touchup tool..

Thanks again, this is very helpful.

Cheers

Lisa


On Sun, Aug 21, 2011 at 11:26 AM, Duff Johnson < <EMAIL REMOVED> >wrote:

> Yes. Heading structure may be found in the tags. In PDF, there's no
> other proper place to look for it (I'm leaving aside a technically
> available but nonetheless pointless option).
>
> Since tags are the only place in which to find the file's logical
> structure (sequence, nesting and semantics), yes, you need
> Acrobat/Reader/3rd party option to use the "tagged reading order".
>
> Tags are essential to accessible PDF, period. The only exception (in a
> purely operational sense) would be a document that is so simple that
> it's possible to have the raw print stream (thanks Karen!) just happen
> to match the document's logical structure.
>
> As such, there is no "rule' about what to do in the absence of tags -
> there are merely a couple of options, both of them bad.
>
> In the case of an untagged PDF, applications can either (a) follow the
> raw print stream or (b) possess the smarts to analyze the page layout
> and make choices that override the as-printed sequence.
>
> An untagged PDF - even if all the content just happens to occur in
> correct reading order - is semantically equivalent to a single giant
> <P> tag containing all the text in the PDF - unacceptable for
> accessibility purposes.
>
> I hope this helps.
>
> Duff Johnson
>
>