texmath-0.12.5: test/writer/mml/msub-12.test

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