Hi Andrew,
On 18/03/2019, at 0:18, "Andrew Cunningham"
<[email protected]<mailto:[email protected]>> wrote:
Ross,
It is also dependent in the fonts themselves and the scripts the language is
written in.
Absolutely.
Depending on the language and script the only way to ensure accessibility is to
include the ActualText attributes for each relevant tag.
Indeed, provided you have supplied tagging at all, as of course should be done.
Considering how complex opentype fonts can become for some scripts the
simplistic To Unicode mappings in a PDF can be insufficient.
Yes, but it is better for the CMaps to at least be appropriate, rather than
inaccurate or missing altogether, as can be the case. Different software tools
get information from different places, so ideally one needs to provide the best
values for all those possible places.
And text in a PDF may by WCAG definition be non-textual content.
Presumably you mean, adding descriptive text to graphics that convey meaningful
information; e.g. a company logo, and most illustrations.
Of course this should be done too. But this can only be useful if the alternate
descriptive text can be found via the structure tagging; hence the need for
fully tagged PDF, navigable via that tagging.
And Zdenek's comment emphasises how what might work well in one language
setting can be quite insufficient for others. We need to be able to accommodate
all things that are helpful.
That is surely what the U (for Universal) means in PDF/UA.
Cheers,
Ross
On Sunday, 17 March 2019, Ross Moore
<[email protected]<mailto:[email protected]>> wrote:
Hi Karljūrgen,
On 17/03/2019, at 1:42, "Karljürgen Feuerherm"
<[email protected]<mailto:[email protected]>> wrote:
> Ross,
>
> Your reply caught my eye, and I am now looking at the pdfx package
> documentation.
>
> May I ask, if accessibility is a concern, why a-2b/-2u rather than -ua-1,
> which seems directly targeted at this?
PDF/UA and PDF/A-1a,2a,3a require a fully tagged PDF.
This is a highly non-trivial task, which requires adding much extra to the
document, done almost entirely through \special commands. The pdfx package does
not provide this, but is useful for meeting the Metadata and other requirements
of these formats.
Abstractly, accessibility is about having sufficient information stored in the
PDF for software tools to be able to build and present a description of the
content and structure, other than the visual one. The same can be said of
software for converting into a different format.
A significant part of this is being able to correctly identify each character
in the fonts used within the TeX/produced PDF. Even this is a non-trivial
problem, due to TeX's non-standard font encodings, and virtual font technique.
>
> Many thanks,
>
> K
>
>> You should use the pdfx package and prepare for PDF/A-2b or -2u.
>> This fixes many of these things that affect conversions, as well as
>> Accessibility and Archivability.
>>
>> It's not fully tagged PDF, but handles many other technical issues.
>>
Hope this helps.
Ross
--
Andrew Cunningham
[email protected]<mailto:[email protected]>
