rec-fn3

(f+g)(z)

W3C sample	WIRIS
	$f g z$

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

Author: MathML 2 Recomendation