<<< mml $$\begin{array}{ccc}\underset{\phantom{\text{fail}}}{\mathrm{HT}}& =& \mathrm{TH}\end{array}$$ >>> native [ EArray [ AlignCenter , AlignCenter , AlignCenter ] [ [ [ EUnder False (EIdentifier "HT") (EPhantom (EText TextNormal "fail")) ] , [ ESymbol Rel "=" ] , [ EIdentifier "TH" ] ] ] ]