an class="constructor">Pctf_extension</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.extension<br>
&nbsp;&nbsp;<span class="keyword">and</span>&nbsp;<span class="keywordsign">'</span>a&nbsp;class_infos&nbsp;=&nbsp;{<br>
&nbsp;&nbsp;&nbsp;&nbsp;pci_virt&nbsp;:&nbsp;<span class="constructor">Asttypes</span>.virtual_flag;<br>
&nbsp;&nbsp;&nbsp;&nbsp;pci_params&nbsp;:&nbsp;(<span class="constructor">Parsetree</span>.core_type&nbsp;*&nbsp;<span class="constructor">Ast