diff --git a/docs/intro_chapter.sgml b/docs/intro_chapter.sgml
index 9ae08b40d77cd9835cc8e81060502070868134b2..5fbf6abb17fb2eb9a944b929c936111b56da23dd 100644
--- a/docs/intro_chapter.sgml
+++ b/docs/intro_chapter.sgml
@@ -116,6 +116,7 @@ LINKEND="RUNNINGPC"> .
     </SECT2>
   </SECT1>
 
+&filetypes;
 &concepts;
 
   <SECT1 ID="CONTRIBUTIONS">