rec-moment1

W3C sample WIRIS
3 0 X 
<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <moment/>
    <degree>
      <cn>3</cn>
    </degree>
    <momentabout>
      <cn>0</cn>
    </momentabout>
    <ci>X</ci>
  </apply>
</math>

Author: MathML 2 Recomendation