<<< native
[ EArray
    [ AlignCenter ]
    [ [ [ EGrouped
            [ EIdentifier "E"
            , ESymbol Rel "="
            , EGrouped
                [ EIdentifier "m"
                , ESymbol Ord "\8290"
                , ESuper (EIdentifier "c") (ENumber "2")
                ]
            ]
        ]
      ]
    ]
]
>>> omml
<?xml version='1.0' ?>
<m:oMathPara>
  <m:oMathParaPr>
    <m:jc m:val="center" />
  </m:oMathParaPr>
  <m:oMath>
    <m:m>
      <m:mPr>
        <m:baseJc m:val="center" />
        <m:plcHide m:val="1" />
        <m:mcs>
          <m:mc>
            <m:mcPr>
              <m:mcJc m:val="center" />
              <m:count m:val="1" />
            </m:mcPr>
          </m:mc>
        </m:mcs>
      </m:mPr>
      <m:mr>
        <m:e>
          <m:r>
            <m:t>E</m:t>
          </m:r>
          <m:r>
            <m:rPr>
              <m:sty m:val="p" />
            </m:rPr>
            <m:t>=</m:t>
          </m:r>
          <m:r>
            <m:t>m</m:t>
          </m:r>
          <m:r>
            <m:rPr>
              <m:sty m:val="p" />
            </m:rPr>
            <m:t>&#8290;</m:t>
          </m:r>
          <m:sSup>
            <m:e>
              <m:r>
                <m:t>c</m:t>
              </m:r>
            </m:e>
            <m:sup>
              <m:r>
                <m:t>2</m:t>
              </m:r>
            </m:sup>
          </m:sSup>
        </m:e>
      </m:mr>
    </m:m>
  </m:oMath>
</m:oMathPara>