value="tex" selected>tex</option>
      <option value="mathml">mathml</option>
      <option value="omml">omml</option>
    </select>
    <label for="to">to</label>
    <select name="to" id="to">
      <option value="tex">tex</option>
      <option value="mathml" selected>mathml</option>
      <option value="omml">omml</option>
      <option value="eqn">eqn</option>
      <option value="typst">typst</option>
    </select>
    <select name="display" id="display">
      <option value="true" selected>display</