Re: [docbook-apps] tagged and accessible PDF document with DocBook

[Tony Graham <tgraham@antenna.co.jp>]

On 27/04/2017 18:27, Dave Pawson wrote:
> On 27 April 2017 at 17:49, Tony Graham <tgraham@antenna.co.jp> wrote:
>
> > Which brings me to...
> >
> > 8. You have a comment about preferring a flat rather than nested ToC
> > structure.  You can represent a hierarchical ToC structure in Tagged
> > PDF, but I don't know whether flat or hierarchical is better for people
> > using assistive technology.  Dave Pawson may know.
>
> I think 'visual' presentation isn't an issue?
> When text is read by a machine, one line with indent x is the same as
> one with indent y.
>
> I'd suggest a flat structure would be more readily accessible, unless
> each entry is numbered etc?

I agree that indenting in the formatted output wouldn't affect how the
text is read out by a machine. However, it seems to me that a
hierarchical structure would give the option of reading/being read only
the top-level ToC entries in turn and then 'expanding' into the ToC
group that is of interest. Presumably any reader software could also
provide options for jumping out of the current ToC group or to the
next/previous ToC group.

The difference between a flat and a hierarchical structure would be like
having the bookmarks sidebar in your PDF viewer permanently expanded or
having it start out collapsed along with only being able to use the
arrow keys to move through the visible entries.

I'll note that the hierarchical EPUB ToC structure derives from the
Digital Talking Book (DTB) NCX structure, but the NISO standard [1]
doesn't provide any rationale for the design. I'll also note that that's
the closest that I can come to finding anything to support the idea that
hierarchical is better.

Regards,


Tony Graham.
--
Senior Architect
XML Division
Antenna House, Inc.
----
Skerries, Ireland
tgraham@antenna.co.jp

[1] http://www.niso.org/workrooms/daisy/Z39-86-2005.html#NCX