<!DOCTYPE html>
<html>
<head>
  <title>mo movablelimits</title>
  <meta charset="utf-8"/>
</head>
<body>
  <math>
    <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>
  <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>
</body>
</html>