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Re: Untagged PDF doc with table structure

for

From: Brian Richwine
Date: Feb 18, 2015 12:19PM

Hi,

I've heard accessibility professionals state that a "tagged pdf" is one
that uses a standard set of tags. So, some PDFs can have structure, but be
using a non-standard set of tags and thus assistive technologies will not
know how to interpret the tags that are in the document. So I came away
thinking that a PDF that has tags is a structured PDF, and even better (in
terms of accessibility) a PDF that uses standardized tags has structure and
is "tagged".

-Brian

On Wed, Feb 18, 2015 at 1:45 PM, Lynn Holdsworth < <EMAIL REMOVED> >
wrote:

> Hi Bevi,
>
> Thanks for taking the time to write such a comprehensive response.
>
> From creating HTML pages for about half a lifetime, I'd define tags
> and structure pretty much the way you do.
>
> But I inferred from this thread, and from talking with someone who
> knows a lot more about PDF than I do, that it's possible to have
> structure without tags in a PDF document. Is this correct, and if so
> how would I recognise it if I were to examine the document's building
> blocks?
>
> Best, Lynn
>
> On 18/02/2015, Chagnon | PubCom < <EMAIL REMOVED> > wrote:
> > 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
> >
> >