union2

(A intersect B) union (C intersect D)

W3C sample	WIRIS
[N/A]	$union intersect A B intersect C D$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <csymbol cd="set1">union</csymbol>
    <apply>
      <csymbol cd="set1">intersect</csymbol>
      <ci>A</ci>
      <ci>B</ci>
    </apply>
    <apply>
      <csymbol cd="set1">intersect</csymbol>
      <ci>C</ci>
      <ci>D</ci>
    </apply>
  </apply>
</math>

Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)