<<< native
[ EText TextNormal "\"string\""
, ESymbol Rel "="
, EText TextNormal "\8220string\8221"
]
>>> omml
<?xml version='1.0' ?>
<m:oMathPara>
  <m:oMathParaPr>
    <m:jc m:val="center" />
  </m:oMathParaPr>
  <m:oMath>
    <m:r>
      <m:rPr>
        <m:nor />
        <m:sty m:val="p" />
      </m:rPr>
      <m:t>&quot;string&quot;</m:t>
    </m:r>
    <m:r>
      <m:rPr>
        <m:sty m:val="p" />
      </m:rPr>
      <m:t>=</m:t>
    </m:r>
    <m:r>
      <m:rPr>
        <m:nor />
        <m:sty m:val="p" />
      </m:rPr>
      <m:t>“string”</m:t>
    </m:r>
  </m:oMath>
</m:oMathPara>