    <munder>
        <mo lspace="0px" rspace="0px" movablelimits="false">A</mo>
        <mi>B</mi>
      </munder>
    </math>
    <math displaystyle="true">
      <munder>
        <mo lspace="0px" rspace="0px" movablelimits="true">A</mo>
        <mi>B</mi>
      </munder>
      <munder>
        <mo lspace="0px" rspace="0px" movablelimits="false">A</mo>
        <mi>B</mi>
      </munder>
    </math>
    <script src="/mathml/support/feature-detection.js"></script>
    <script>MathMLFeatureDetection.ensure_fo