
      of conflicts when you need to incorporate your changes back onto the
      trunk.</p>
    </dd>

    <dt>An older revision of the trunk</dt>

    <dd>
      <p>There are a number of reasons why you may need to do this. For
      example:</p>

      <ul>
        <li>You are using a stable version to act as your <em>control</em>
        data.</li>

        <li>You need to know that your baseline is well tested (e.g. scientific
        changes).</li>

        <li>Your change may need to be merged with o