texmath-0.6.7: tests/writers/munderover-03.tex
\underset{\mathrm{under\ script}}{\overset{\phantom{\mathrm{fail}}}{\mathrm{\_\ \ baseline\ \_\ }}}=\underset{\mathrm{under\ script}}{\mathrm{\_\ \ baseline\ \_\ }}\underset{\mathrm{under\ script}}{\overset{\phantom{\mathrm{fail}}}{\mathrm{\_\ \ baseline\ \_\ }}}=\underset{\mathrm{under\ script}}{\mathrm{\_\ \ baseline\ \_\ }}