tendsto type = 'below' with <reln>
<math xmlns="http://www.w3.org/1998/Math/MathML">
<reln>
<tendsto type="below"/>
<apply>
<power/>
<ci>x</ci>
<cn>2</cn>
</apply>
<apply>
<power/>
<ci>a</ci>
<cn>2</cn>
</apply>
</reln>
</math>
Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)