<br>
&nbsp;&nbsp;<span class="keyword">type</span>&nbsp;port_type&nbsp;=<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">GP_PORT_NONE</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">GP_PORT_SERIAL</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">GP_PORT_USB</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">GP_PORT_DISK</span><br>
&nbsp;