try copy

testfiles-lua/test_struct2.pvt

@@ -0,0 +1,59 @@
+\ExplSyntaxOn
+\sys_gset_rand_seed:n{42}
+\ExplSyntaxOff
+\DocumentMetadata{
+  uncompress,
+  pdfversion = 2.0,
+  testphase = phase-I,
+}
+\input{regression-test}
+\documentclass{article}
+\usepackage[structelem]{luamml-demo}
+
+\usepackage{unicode-math}
+
+\begin{document}
+\tagstructbegin{tag=Document}
+
+\tagstructbegin{tag=P}
+\tagmcbegin{tag=P}
+hello
+\tagmcend
+\tagstructend
+
+\LuaMMLTagAF{} {
+\[
+  \begin{pmatrix}
+    1 & 0 & 0 \\
+    0 & 1 & 0 \\
+    0 & 0 & 1
+  \end{pmatrix}
+  =
+  \begin{cases}
+    1 & \text{if $a=b$} \\
+    2 & \text{else}
+  \end{cases}
+\]
+}
+\LuaMMLTagAF{} {
+\[
+  x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}.
+\]
+}
+\LuaMMLTagAF{} {
+\[
+  \sum_a\underline c\dot bc'
+\]
+}
+
+\LuaMMLTagAF{} {
+\begin{align}
+  abc&=def & e^{\mathrm{i}\pi}&=-1\\
+  \Big(1+2&=3\Big)\\
+  5
+\end{align}
+}
+
+Es gilt \LuaMMLTagAF{}{$\sin(x)-\sin(x+2\pi)=0$}.
+\tagstructend
+\end{document}