texmath-0.7: tests/writers/munderover-06.tex
\underset{second\ one}{\overset{first\ overscript}{\underset{first\ under\ script}{\overset{second\ overscript}{BASE}}}} = \underset{second\ one}{\overset{first\ overscript}{\overset{second\ overscript}{\underset{first\ under\ script}{BASE}}}}