<<< native
[ EArray
    [ AlignLeft ]
    [ [ [ EText TextNormal "default: (accent=true)" ] ]
    , [ [ EGrouped
            [ EUnder False (EIdentifier "H") (ESymbol Accent "'")
            , EUnder False (EIdentifier "H") (ESymbol Accent "^")
            , EUnder False (EIdentifier "H") (ESymbol Accent "_")
            , EUnder False (EIdentifier "H") (ESymbol Accent "`")
            , EUnder False (EIdentifier "H") (ESymbol Accent "~")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\168")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\175")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\180")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\184")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\710")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\711")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\728")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\729")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\730")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\732")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\733")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\770")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\785")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8254")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8411")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8412")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8592")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8594")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8596")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8636")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8637")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8640")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8641")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9140")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9141")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9180")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9181")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9182")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\9183")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\10574")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\10576")
            ]
        ]
      ]
    , [ [ EText TextNormal "accent=false:" ] ]
    , [ [ EGrouped
            [ EUnder False (EIdentifier "H") (ESymbol Ord "'")
            , EUnder False (EIdentifier "H") (ESymbol Ord "^")
            , EUnder False (EIdentifier "H") (ESymbol Ord "_")
            , EUnder False (EIdentifier "H") (ESymbol Ord "`")
            , EUnder False (EIdentifier "H") (ESymbol Ord "~")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\168")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\175")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\180")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\184")
            , EUnder False (EIdentifier "H") (ESymbol Alpha "\710")
            , EUnder False (EIdentifier "H") (ESymbol Alpha "\711")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\728")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\729")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\730")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\732")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\733")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\770")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\785")
            , EUnder False (EIdentifier "H") (ESymbol Ord "\8254")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8411")
            , EUnder False (EIdentifier "H") (ESymbol Accent "\8412")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8592")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8594")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8596")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8636")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8637")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8640")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\8641")
            , EUnder False (EIdentifier "H") (ESymbol TOver "\9140")
            , EUnder False (EIdentifier "H") (ESymbol TUnder "\9141")
            , EUnder False (EIdentifier "H") (ESymbol TOver "\9180")
            , EUnder False (EIdentifier "H") (ESymbol TUnder "\9181")
            , EUnder False (EIdentifier "H") (ESymbol TOver "\9182")
            , EUnder False (EIdentifier "H") (ESymbol TUnder "\9183")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\10574")
            , EUnder False (EIdentifier "H") (ESymbol Rel "\10576")
            ]
        ]
      ]
    ]
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mtable>
    <mtr>
      <mtd columnalign="left" style="text-align: left">
        <mtext mathvariant="normal">default: (accent=true)</mtext>
      </mtd>
    </mtr>
    <mtr>
      <mtd columnalign="left" style="text-align: left">
        <mrow>
          <munder>
            <mi>H</mi>
            <mo accent="true">&#39;</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">^</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">_</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">`</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">~</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¨</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¯</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">´</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¸</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">ˆ</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">ˇ</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˘</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˙</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˚</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˝</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">̂</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">̑</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">‾</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⃛</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⃜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">←</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">→</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↔</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↼</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↽</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⇀</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⇁</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⎴</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⎵</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏝</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏞</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏟</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⥎</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⥐</mo>
          </munder>
        </mrow>
      </mtd>
    </mtr>
    <mtr>
      <mtd columnalign="left" style="text-align: left">
        <mtext mathvariant="normal">accent=false:</mtext>
      </mtd>
    </mtr>
    <mtr>
      <mtd columnalign="left" style="text-align: left">
        <mrow>
          <munder>
            <mi>H</mi>
            <mo accent="true">&#39;</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">^</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">_</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">`</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">~</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¨</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¯</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">´</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">¸</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">ˆ</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">ˇ</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˘</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˙</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˚</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">˝</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">̂</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">̑</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">‾</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⃛</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⃜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">←</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">→</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↔</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↼</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">↽</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⇀</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⇁</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⎴</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⎵</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏜</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏝</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏞</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⏟</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⥎</mo>
          </munder>
          <munder>
            <mi>H</mi>
            <mo accent="true">⥐</mo>
          </munder>
        </mrow>
      </mtd>
    </mtr>
  </mtable>
</math>