rec-degree1

W3C sample	WIRIS
	$\frac{\partial^{n+m}\sin (xy)}{\partial x^n\partial y^m}$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <partialdiff/>
    <bvar>
      <ci>x</ci>
      <degree>
        <ci>n</ci>
      </degree>
    </bvar>
    <bvar>
      <ci>y</ci>
      <degree>
        <ci>m</ci>
      </degree>
    </bvar>
    <apply>
      <sin/>
      <apply>
        <times/>
        <ci>x</ci>
        <ci>y</ci>
      </apply>
    </apply>
  </apply>
</math>

Author: MathML 2 Recommendation