We sent the 2025-06-01 release of the LaTeX kernel to CTAN over the weekend. It will be appearing to most users via TeX Live about now, and shortly in MiKTeX.
News from the tagging project
Work continues on the tagging project, and this release sees major work on tagging mathematics, with automatic generation of MathML now available in LuaTeX. The MathML can then be used as an Associated File (AF) for PDF 2.0 output: a big step in providing accessible mathematics. There are (as usual) some caveats at present, but for many cases, this is already very usable.
Tagging is now easier to turn on, as we’ve improved the keys to
\DocumentMetadata: all you need now is
\DocumentMetadata{lang = ..., tagging = on}
This change emphasises that we are now at the stage where a tagging is becoming less experimental and more routinely-usable.
We’ve adjusted the standard PDF output: it’s now PDF 2.0 when tagging. That’s because PDF 2.0 is much better for tagging than PDF 1.x: but you can still request the older output format.
Other improvements in tagging are there, of course, most notably addressing some spacing oddities following display math mode.
Improving marks and output routine
A few releases ago, we integrated a new marks mechanism into the kernel, but
left the classical approach available as a separate code path. That has now
been addressed: the older interfaces now use the new mechanism, and multiple
mark classes can be used with, for example, multicol.
The marks code was originally developed many (many) years ago as part of work on a new output routine (OR). Whilst today we don’t plan quite such radical changes, we are improving the OR. To support accessibility, we need to integrate a number of hooks, and this is an opportunity to refactor the OR to use the socket/plug approach. This should make the OR much easier to control without needing to completely replace it.
Other improvements and changes
The newsletter also covers various other small enhancements or corrections that we provide with the June release.
Enjoy – Joseph