<<< mml $${\mathrm{H}}_2=\stackrel{\phantom{x}}{{\mathrm{H}}_2}$$ >>> native [ ESub (EIdentifier "H") (ESymbol Ord "2") , ESymbol Rel "=" , EOver False (ESub (EIdentifier "H") (ESymbol Ord "2")) (EPhantom (EIdentifier "x")) ]