<<< native
[ EArray
    [ AlignCenter , AlignCenter , AlignCenter ]
    [ [ [ EIdentifier "a" ]
      , [ EIdentifier "b" ]
      , [ EIdentifier "c" ]
      ]
    , [ [ EIdentifier "x" ]
      , [ EIdentifier "y" ]
      , [ EIdentifier "z" ]
      ]
    , [ [ ENumber "1" ] , [ ENumber "2" ] , [ ENumber "3" ] ]
    ]
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mtable>
    <mtr>
      <mtd columnalign="center">
        <mi>a</mi>
      </mtd>
      <mtd columnalign="center">
        <mi>b</mi>
      </mtd>
      <mtd columnalign="center">
        <mi>c</mi>
      </mtd>
    </mtr>
    <mtr>
      <mtd columnalign="center">
        <mi>x</mi>
      </mtd>
      <mtd columnalign="center">
        <mi>y</mi>
      </mtd>
      <mtd columnalign="center">
        <mi>z</mi>
      </mtd>
    </mtr>
    <mtr>
      <mtd columnalign="center">
        <mn>1</mn>
      </mtd>
      <mtd columnalign="center">
        <mn>2</mn>
      </mtd>
      <mtd columnalign="center">
        <mn>3</mn>
      </mtd>
    </mtr>
  </mtable>
</math>