rec-plus5

W3C sample	WIRIS
	$x+y+z$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <plus/>
    <ci>x</ci>
    <ci>y</ci>
    <ci>z</ci>
  </apply>
</math>

Author: MathML 2 Recommendation