texmath-0.6.7: tests/writers/munder-01.tex
\underset{\mathrm{under}}{\mathrm{BASE}}=\underset{\phantom{\mathrm{under}}}{\underset{\mathrm{under}}{\mathrm{BASE}}}\underset{\mathrm{under}}{\mathrm{BASE}}=\underset{\phantom{\mathrm{under}}}{\underset{\mathrm{under}}{\mathrm{BASE}}}