Fully Tagged PDF (even for math) is in the works for LaTeX [LWN.net]

Fully Tagged PDF (even for math) is in the works for LaTeX

Posted Sep 19, 2025 19:04 UTC (Fri) by notriddle (subscriber, #130608)
In reply to: Fully Tagged PDF (even for math) is in the works for LaTeX by jschrod
Parent article: Typst: a possible LaTeX replacement

If Typst manages to steal mindshare from LaTeX, I doubt it'll have much to do with tagged pdf or other niche features. It'll happen because, if I forget a closing brace, pdflatex does this:

This is pdfTeX, Version 3.141592653-2.6-1.40.24 (TeX Live 2022/Debian) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./t.latex
LaTeX2e <2022-11-01> patch level 1
L3 programming layer <2023-01-16>
(/usr/share/texlive/texmf-dist/tex/latex/base/article.cls
Document Class: article 2022/07/02 v1.4n Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/size12.clo))
(/usr/share/texlive/texmf-dist/tex/latex/l3backend/l3backend-pdftex.def)
(./t.aux))
Runaway argument?
{ripe and green) \end {enumerate} \end {document} \par 
! File ended while scanning use of \emph .
<inserted text>
                \par 
<*> t.latex
           
?

And Typst does this:

error: unclosed delimiter
   ┌─ t.typst:14:12
   │
14 │ + #underline[Good gin  
   |             ^

In TeX's defense, it's not the worst system I've ever dealt with, and a lot of that spew can be cleaned up by just putting it behind a --verbose flag, but the biggest, hardest-to-fix problem is here:

{ripe and green) \end {enumerate} \end {document} \par

Typest's equivalent has a line number. It also actually matches what was written. Is that fixable without breaking changes to the macro system?

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Fully Tagged PDF (even for math) is in the works for LaTeX

Posted Sep 22, 2025 18:49 UTC (Mon) by jschrod (subscriber, #1646) [Link]

You chose to use the one example of an error message that comes without a line number.

In all other error messages TeX's error messages consist of two lines. The first line has the line number and all characters that are read up to the error, the second line has the characters that are still to be processed.

But that is actually a bynote. You wrote

> tagged pdf or other niche features

Since journals (especial scientific journals that Lee wrote about) and other publishers increasingly demand the production of barrier free PDFs for online publication, Tagged PDF is not a niche feature, IMNSHO. Customers of mine currently pour 6-digit numbers of Euro in creation of such files. For private production it doesn't matter -- but for publication, it will soon be a must-have.