msubsup-03.test

<<< native
[ ESubsup (EIdentifier "L") (EIdentifier "x") (ENumber "2")
, ESymbol Rel "="
, ESubsup
    (EIdentifier "L")
    (ESub (EIdentifier "x") (EPhantom (EIdentifier "z")))
    (ESuper (ENumber "2") (EPhantom (EIdentifier "z")))
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <msubsup>
      <mi>L</mi>
      <mi>x</mi>
      <mn>2</mn>
    </msubsup>
    <mo>=</mo>
    <msubsup>
      <mi>L</mi>
      <msub>
        <mi>x</mi>
        <mphantom>
          <mi>z</mi>
        </mphantom>
      </msub>
      <msup>
        <mn>2</mn>
        <mphantom>
          <mi>z</mi>
        </mphantom>
      </msup>
    </msubsup>
  </mrow>
</math>