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

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">  <munderover>    <mrow>      <munderover>        <mi mathvariant="normal">BASE</mi>         <mi mathvariant="normal">first under script</mi>         <mi mathvariant="normal">second overscript</mi>       </munderover>     </mrow>     <mi mathvariant="normal">second one</mi>     <mi mathvariant="normal">first overscript</mi>   </munderover>   <mo>=</mo>   <munderover>    <mrow>      <mover>        <mrow>          <munder>            <mi mathvariant="normal">BASE</mi>             <mi mathvariant="normal">first under script</mi>           </munder>         </mrow>         <mi mathvariant="normal">second overscript</mi>       </mover>     </mrow>     <mi mathvariant="normal">second one</mi>     <mi mathvariant="normal">first overscript</mi>   </munderover> </math>