span class="ts23">identifier</span><span class="ts4">&gt;</span><span class="ts3">&nbsp;and </span><span class="ts4">&lt;IF NOT_DEFINED_</span><span class="ts23">identifier</span><span class="ts4">&gt;</span><span class="ts3">&nbsp;tokens. For example:</span></p>
      <p><span class="ts3">&nbsp;</span></p>
      <p class="ps22"><span class="ts4">(IO_OPEN_UPD),</span></p>
      <p class="ps22"><span class="ts4">begin</span></p>
      <p class="ps22">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;