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

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">  <munderover>    <mi mathvariant="normal">BASE</mi>     <mi mathvariant="normal">s</mi>     <mi mathvariant="normal">t</mi>   </munderover>   <mo>=</mo>   <munderover>    <mi mathvariant="normal">BASE</mi>     <mrow>      <mphantom>        <mn>1</mn>
      </mphantom>
      <mi mathvariant="normal">s</mi>
      <mphantom>
        <mn>1</mn>
      </mphantom>
    </mrow>     <mrow>      <mphantom>        <mn>1</mn>
      </mphantom>
      <mi mathvariant="normal">t</mi>
      <mphantom>
        <mn>1</mn>
      </mphantom>
    </mrow>   </munderover> </math>