Formatting of right hand side of equation should be identical to formatting of left hand side
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<msub>
<mi>A</mi>
<mi>B</mi>
</msub>
<mo>=</mo>
<msub>
<mrow>
<mi>A</mi>
</mrow>
<mrow>
<mi>B</mi>
</mrow>
</msub>
</math>
Author: George Chavchanidze, Opera Software ASA