texmath-0.6.7: tests/writers/munderover-10.tex
\underset{\mathrm{under}}{\overset{\mathrm{over}}{\mathrm{B}}}=\overset{\mathrm{over}}{\underset{\mathrm{under}}{\mathrm{B}}}\underset{\mathrm{under}}{\overset{\mathrm{over}}{\mathrm{B}}}=\overset{\mathrm{over}}{\underset{\mathrm{under}}{\mathrm{B}}}