mfenced-01.test

<<< native
[ EDelimited
    "["
    "]"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter , AlignCenter ]
           [ [ [ EIdentifier "A" ]
             , [ EIdentifier "B" ]
             , [ EIdentifier "C" ]
             ]
           , [ [ EIdentifier "D" ]
             , [ EIdentifier "E" ]
             , [ EIdentifier "F" ]
             ]
           , [ [ EIdentifier "G" ]
             , [ EIdentifier "H" ]
             , [ EIdentifier "I" ]
             ]
           ])
    ]
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <mo stretchy="true" form="prefix">[</mo>
    <mtable>
      <mtr>
        <mtd columnalign="center" style="text-align: center">
          <mi>A</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>B</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>C</mi>
        </mtd>
      </mtr>
      <mtr>
        <mtd columnalign="center" style="text-align: center">
          <mi>D</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>E</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>F</mi>
        </mtd>
      </mtr>
      <mtr>
        <mtd columnalign="center" style="text-align: center">
          <mi>G</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>H</mi>
        </mtd>
        <mtd columnalign="center" style="text-align: center">
          <mi>I</mi>
        </mtd>
      </mtr>
    </mtable>
    <mo stretchy="true" form="postfix">]</mo>
  </mrow>
</math>