<?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">under script</mi>     <mi mathvariant="normal">over script</mi>   </munderover>   <mo>=</mo>   <munder>    <mrow>      <mover>        <mi mathvariant="normal">BASE</mi>         <mi mathvariant="normal">over script</mi>       </mover>     </mrow>     <mi mathvariant="normal">under script</mi>   </munder> </math>