<<< native [ EIdentifier "- middle -" , ESymbol Rel "=" , EOver False (EOver False (EIdentifier "- middle -") (EPhantom (EIdentifier "fail"))) (EPhantom (EIdentifier "fail")) ] >>> mml $$\mathrm{-\; middle\; -}=\stackrel{\phantom{\mathrm{fail}}}{\stackrel{\phantom{\mathrm{fail}}}{\mathrm{-\; middle\; -}}}$$