texmath-0.12.5: test/writer/mml/msub-02.test

<<< native
[ ESub
    (EGrouped [ EPhantom (EIdentifier "fail") , EIdentifier "X" ])
    (ENumber "0")
, ESymbol Rel "="
, ESub (EIdentifier "X") (ENumber "0")
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <msub>
      <mrow>
        <mphantom>
          <mi>fail</mi>
        </mphantom>
        <mi>X</mi>
      </mrow>
      <mn>0</mn>
    </msub>
    <mo>=</mo>
    <msub>
      <mi>X</mi>
      <mn>0</mn>
    </msub>
  </mrow>
</math>