rec-ci3

x of a

W3C sample	WIRIS
	$x_{a}$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <ci>
    <msub>
      <mi>x</mi>
      <mi>a</mi>
    </msub>
  </ci>
</math>

Author: MathML 2 Recommendation