<<< omml
<?xml version="1.0" encoding="UTF-8"?>
<m:oMathPara>
  <m:oMathParaPr>
    <m:jc m:val="center" />
  </m:oMathParaPr>
  <m:oMath>
    <m:d>
      <m:dPr>
        <m:begChr m:val="{" />
        <m:endChr m:val="}" />
        <m:grow />
      </m:dPr>
      <m:e>
        <m:f>
          <m:fPr>
            <m:type m:val="noBar" />
          </m:fPr>
          <m:num>
            <m:r>
              <m:rPr>
                <m:sty m:val="p" />
              </m:rPr>
              <m:t>x</m:t>
            </m:r>
          </m:num>
          <m:den>
            <m:r>
              <m:rPr>
                <m:sty m:val="p" />
              </m:rPr>
              <m:t>y</m:t>
            </m:r>
          </m:den>
        </m:f>
      </m:e>
    </m:d>
  </m:oMath>
</m:oMathPara>

>>> native
[ EDelimited
    "{"
    "}"
    [ Right (EFraction NoLineFrac (EIdentifier "x") (EIdentifier "y"))
    ]
]