Hi Steffen

The new manuals should help to create PDFs that pass VeraPDF. I have managed to 
make three large sets of lecture notes ‘accessible’ that are heavy on math and 
images.
I have encountered a few glitches (for instance, with \setuphead using before= 
and after=).
 I’ll be happy to give you access to the complete sources if you think this 
will be helpful.

Canvas uses Ally to check PDFs, and the accessibility score I can get with it 
is about 50%. Mikael has looked into this, and he wrote earlier on the mailing 
list:

> I am sorry. Canvas uses the Ally checker, and the specification of
> what it does and does not is simply not available. In particular, it
> does not follow UA-2. (Maybe more something like PDF1.X). The title is
> in the file, but not in the place where Ally is expecting it (and
> there it is not, as far as I understand, compatible with UA-2...).
> 
> Joseph from the LaTeX team wrote on their forum, see
> https://usergroup.ally.ac/s/discussion/post/post/view?id=2362
> 
> We also have Canvas at our university. I have written to the
> accessibility people at our university and explained that the tool
> they pay for is not good for the purpose.
> 
> There will be no work from our side to try to satisfy the Ally
> checker. It is a black box.
> 
> /Mikael


My institution is currently satisfied if I provide them with VeraPDF-certified, 
UA-2 compliant PDFs…

There is another issue with PDFs compiled with

\setupbackend[format=pdf/ua-2]
\setuptagging
 [state=start,
  preset=basic,
  level=2,
        option=interaction
]

That I have not been able to figure out: All viewers I have tried on my Mac 
crash when opening large PDFs that are compiled this way, typically when I 
reach a page that contains a figure.
With one exception: Acrobat. I don’t know whether it’s ConTeXt or the readers 
that struggle with accessible PDFs. 
It also only happens with larger PDFs (50+ pages, maybe) 
The viewers work fine when I compile the files without the accessibility 
preamble.

Best,

Matthias






> On Nov 16, 2025, at 1:11 AM, Pablo Rodriguez via ntg-context 
> <[email protected]> wrote:
> 
> On 11/15/25 20:52, Steffen Wolfrum wrote:
>> Hi Pablo,
>> 
>> Thanks you very much for mentioning these manuals. Great, I didn't know
>> they are there, but now I found them.
> 
> Hi Steffen,
> 
> on a second thought, I wonder whether \setupbackend[format=pdf/ua-2]
> might give you better results.
> 
> Just in case it might help,
> 
> Pablo
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