\DocumentMetadata: Producing tagged PDF output ¶The \DocumentMetadata command was added to LaTeX in 2022.
It enables so-called “tagging” of the PDF output, aiding
accessibility of the PDF. It is supported best with LuaLaTeX;
pdfLaTeX and XeLaTeX are supported as well as possible
(see TeX engines).
It is unlike nearly any other command in LaTeX in that it must
occur before the \documentclass command that starts a LaTeX
document proper (see \documentclass). Therefore it must be
called with \RequirePackage rather than \usepackage
(see \RequirePackage).
This support is still in development, so we will not try to list all
the possible settings. Please see the
documentmetadata-support-doc document, part of the
latex-lab package (https://ctan.org/pkg/latex-lab). Here
is a simple example which enables most tagging currently implemented:
\DocumentMetadata{testphase={phase-III,firstaid}}
\documentclass{article}
...
As you can see from the key name testphase, this is all still
in an experimental phase. The LaTeX developers strongly encourage
users to give it a try and report problems, so it can be improved.