texmath-0.10: tests/writers/mfenced-06.tex
\left\lbrack \begin{matrix}
U \\
V \\
\end{matrix} \right| = \left| \begin{matrix}
U \\
V \\
\end{matrix} \right\rbrack
\left\lbrack \begin{matrix}
U \\
V \\
\end{matrix} \right| = \left| \begin{matrix}
U \\
V \\
\end{matrix} \right\rbrack