th>group</th>
      <td><p>values or field name of a grouping variable to break quantile computations up by</p></td>
    </tr>
    <tr>
      <th>data</th>
      <td><p>an optional data frame, providing the source for x</p></td>
    </tr>
    <tr>
      <th>probs</th>
      <td><p>numeric vector of probabilities with values in <code>[0,1]</code> at which to compute quantiles - if <code>NULL</code>, every point of <code>x</code> is a quantile</p></td>
    </tr>
    <tr>
      <th>distn</th>
      <td><p>quan