<<< mml
<?xml version="1.0" encoding="UTF-8"?>

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <mi>x</mi> 
    <mover>
      <mo> &#x2192;</mo> 
      <mtext>maps to</mtext> 
    </mover> 
    <mi>y</mi> 
  </mrow> </math>
>>> native
[ EIdentifier "x"
, EOver False (ESymbol Accent "\8594") (EText TextNormal "maps to")
, EIdentifier "y"
]