ctor with zeroes is added by default.</p></td>
    </tr>
    <tr>
      <th>slopes</th>
      <td><p>A numeric vector, which contains the slope parameters for each item - one parameter per item is expected.</p></td>
    </tr>
    <tr>
      <th>lowerA</th>
      <td><p>A numeric vector, which contains the lower asymptote parameters (kind of guessing parameter) for each item. In the case of polytomous items, the value must be 0.</p></td>
    </tr>
    <tr>
      <th>upperA</th>
      <td><p>numeric vector, w