texmath-0.7: tests/writers/munderover-07.tex
\underset{under-2}{\overset{over-1}{\underset{under-1}{\overset{over-2}{BASE}}}} = \underset{under-2}{\overset{over-1}{\underset{under-1}{\overset{over-2}{BASE}}}}
\underset{under-2}{\overset{over-1}{\underset{under-1}{\overset{over-2}{BASE}}}} = \underset{under-2}{\overset{over-1}{\underset{under-1}{\overset{over-2}{BASE}}}}