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Re: Untagged PDF doc with table structure

for

From: Lynn Holdsworth
Date: Feb 18, 2015 11:45AM

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
>
>