[NTG-context] Re: Tagging Math

10 Apr 2025

      Thank you Mikael,

What I would like to to is to have what \placenotes[mathnote] produces added to the pdf as a tag so that a screen reader would be able to read the math. Right now,
with your example, it reads the typeset math in an extremely garbled way (but the mathnotes at leats make sense).

So the question is how to get the content of the mathnotes into the PDF tags…

Matthias
...
On Apr 10, 2025, at 2:20 PM, Mikael Sundqvist  wrote:
Hi,
I don't know what you expect, but you can try
%%%
\setupbackend[format=pdf/ua-2]
\setuptagging[state=start]
\registermathsymbol[default][en]["1D467][the variable]
\registermathsymbol[default][en]["1D458][the index]
\enabletrackers[math.textblobs]
\setupnote
 [mathnote]
 [location=margin]
\starttext
\startformula
 \abs {(z__0 + h)^n -  z__0^n }
 \alignhere
 = \abs {\sum_{k = 1}^n \binom{n}{k} h^k z__0^{n - k} }
 \breakhere
 = \abs {h \sum_{k = 0}^{n - 1} \binom{n}{k + 1} h^k z__0^{n - 1 - k} }
 \breakhere
 = \abs {h \sum_{k = 0}^{n - 1} \frac {n}{k + 1} \binom{n - 1}{k} h^k
z__0^{n - 1 - k} }
 \breakhere
 \le  n \abs{h} \sum_{k = 0}^{n - 1}  \binom{n - 1}{k} \abs{h}^k
\abs{z__0}^{n - 1 - k}
 \breakhere
 \le  n \abs{h} (\abs{z__0} + \abs{h})^{n - 1}
\stopformula
\placenotes[mathnote]
\registermathsymbol[default][en][lowercasebold][the vector]
\startformula
 (\alpha + \beta) \mathbf{u} = \alpha \mathbf{u} + \beta \mathbf{u}
\stopformula
\placenotes[mathnote]
\stoptext
%%%
As you see in the text the z and k are now interpreted as variable and
index. The second example gives "the vector" for all lowercasebold.
I will not paste the mathml blob from the bigger formula, but the
smaller one looks like this:
<math>
<mrow>
<mo stretchy="false">(</mo>
<mi>𝛼</mi>
<mo>+</mo>
<mi>𝛽</mi>
<mo stretchy="false">)</mo>
<mi>𝐮</mi>
<mo>=</mo>
<mi>𝛼</mi>
<mi>𝐮</mi>
<mo>+</mo>
<mi>𝛽</mi>
<mi>𝐮</mi>
</mrow>
</math>
/Mikael
On Thu, Apr 10, 2025 at 7:58 PM Matthias Weber
 wrote:
...
Dear All,
Following the instructions in tagging.pdf,
I tried
\setupbackend[format=pdf/ua-2]
\setuptagging[state=start]
\enabledirectives [backend.usetags=crap]
\registermathsymbol[default][en][ z ][the variable]
\registermathsymbol[default][en][ k ][the index]
\starttext
\startformula
\startalign
\NC \left|(z_0+h)^n -  z_0^n\right| \NC = \left|\sum_{k=1}^n \binom{n}{k}h^k z_0^{n-k}\right| \NR
\NC \NC =  \left |h \sum_{k=0}^{n-1} \binom{n}{k+1} h^k z_0^{n-1-k}\right| \NR
\NC \NC =  \left|h \sum_{k=0}^{n-1} \frac n {k+1} \binom{n-1}{k} h^k z_0^{n-1-k}\right| \NR
\NC \NC \le  n | h| \sum_{k=0}^{n-1}  \binom{n-1}{k} |h|^k |z_0|^{n-1-k} \NR
\NC \NC \le  n | h|   (|z_0|+|h|)^{n-1}  \NR
\stopalign
\stopformula
\stoptext
This creates within the pdf the XML attachment below:
This XML  contains all the information from the formula. Wrapping it into
\usemodule[mathml]
\starttext
\xmlprocessdata{}{
% content of XML file
}{}
\stoptext
produces
which is also what my Mac screen reads from the original PDF, but it is evidently not what I want.
Does someone have a working example that shows how to do this right?
Thanks,
Matthias
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