diff --git a/src/doc/user/usermanual.sgml b/src/doc/user/usermanual.sgml
index 5acc4386..1adef3c9 100644
--- a/src/doc/user/usermanual.sgml
+++ b/src/doc/user/usermanual.sgml
@@ -366,6 +366,39 @@
           in the <command>recoll</command> GUI. It is stored in the
           <filename>missing</filename> text file inside the configuration
           directory.</para>
+
+        <para>By default, &RCL; will try to index any file type that
+          it has a way to read. This is sometimes not desirable, and
+          there are ways to either exclude some types, or on the
+          contrary to define a positive list of types to be
+          indexed. In the latter case, any type not in the list will
+          be ignored.</para>
+        <para>Excluding types can be done by adding name patterns to
+          the <literal>skippedNames</literal> list, which can be done
+          from the GUI Index configuration menu. It is also possible
+          to exclude a mime type independantly of the file name by
+          associating it with the <filename>rclnull</filename>
+          filter. This can be done by editing
+          the <link linkend="RCL.INSTALL.CONFIG.MIMECONF"> 
+            <filename>mimeconf</filename> configuration
+            file</link>.</para>
+
+        <para>In order to define a positive list, You need to edit the 
+          <link linkend="RCL.INSTALL.CONFIG.RECOLLCONF">main
+            configuration file
+            (<filename>recoll.conf</filename>)</link> and set
+            the <literal>indexedmimetypes</literal> configuration
+            variable. Example:<programlisting>
+indexedmimetypes = text/html application/pdf
+          </programlisting>
+          There is no GUI way to do this, because this option runs a
+          bit contrary to &RCL; main goal which is to help you find
+          information, independantly of how it may be stored.
+        </para>
+
+
+
+
       </sect2>