Tagging of xform objects with internal tagging

[u-fischer]

\DocumentMetadata{tagging = on,uncompress}
\documentclass{article}

\begin{document}

start 

\ExplSyntaxOn
\leavevmode\pdfxform_new:nnn{test}{}{some text with \emph{tagging}}
\pdfxform_use:n{test}
\ExplSyntaxOff

middle

stop
\end{document}

pdflatex

this errors as the delayed shipout writing of the labels does not work for the xform: the abspage is wrong and the mcid are not correctly numbered:

\new@label@record{mcid-3}{{tagabspage}{0}{tagmcabs}{3}{tagmcid}{0}}  %<------
\new@label@record{mcid-4}{{tagabspage}{0}{tagmcabs}{4}{tagmcid}{1}}  %<------
\new@label@record{mcid-1}{{tagabspage}{1}{tagmcabs}{1}{tagmcid}{0}}
\new@label@record{mcid-2}{{tagabspage}{1}{tagmcabs}{2}{tagmcid}{1}}
\new@label@record{mcid-5}{{tagabspage}{1}{tagmcabs}{5}{tagmcid}{2}}
\new@label@record{mcid-6}{{tagabspage}{1}{tagmcabs}{6}{tagmcid}{3}}

lualatex

With lualatex it compiles but the Xobject has no internal structure or MCID, and the Em that is created has no kid.

Currently only xform objects without tagging should be used and at use they should be wrapped into a Figure.