<<< mml
<?xml version="1.0" encoding="UTF-8"?>

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">  <mtable frame="solid">    <mtr>      <mtd>        <mphantom>          <mtext>fail</mtext>
        </mphantom>         <munder>          <mi mathvariant="normal">HT</mi>           <mphantom>            <mtext>fail</mtext>
          </mphantom>         </munder>       </mtd>       <mtd>        <mo>=</mo>       </mtd>       <mtd>        <mover>          <mi mathvariant="normal">TH</mi>           <mphantom>            <mtext>fail</mtext>
          </mphantom>         </mover>         <mphantom>          <mtext>fail</mtext>
        </mphantom>       </mtd>     </mtr>   </mtable> </math>
>>> native
[ EArray
    [ AlignCenter , AlignCenter , AlignCenter ]
    [ [ [ EGrouped
            [ EPhantom (EText TextNormal "fail")
            , EUnder
                False (EIdentifier "HT") (EPhantom (EText TextNormal "fail"))
            ]
        ]
      , [ ESymbol Rel "=" ]
      , [ EGrouped
            [ EOver
                False (EIdentifier "TH") (EPhantom (EText TextNormal "fail"))
            , EPhantom (EText TextNormal "fail")
            ]
        ]
      ]
    ]
]