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

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">  <mover>    <mi mathvariant="normal">BASE</mi>     <mi mathvariant="normal">over script</mi>   </mover>   <mo>=</mo>   <mover>    <mrow>      <mover>        <mrow>          <mover>            <mi mathvariant="normal">BASE</mi>             <mi mathvariant="normal">over script</mi>           </mover>         </mrow>         <mphantom>          <mi mathvariant="normal">over</mi>
        </mphantom>       </mover>     </mrow>     <mphantom>      <mi mathvariant="normal">over</mi>
    </mphantom>   </mover> </math>