rec-compose2

W3C sample	WIRIS
	$f g h$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <compose/>
    <ci type="fn">f</ci>
    <ci type="fn">g</ci>
    <ci type="fn">h</ci>
  </apply>
</math>

Author: MathML 2 Recommendation