diff --git a/doc/src/sgml/textsearch.sgml b/doc/src/sgml/textsearch.sgml
new file mode 100644
index ef228e3..46db103
*** a/doc/src/sgml/textsearch.sgml
--- b/doc/src/sgml/textsearch.sgml
*************** ts_rank(<optional> <replaceable class="P
*** 867,873 ****
  
        <listitem>
         <para>
!         Standard ranking function.<!-- TODO document this better -->
         </para>
        </listitem>
       </varlistentry>
--- 867,873 ----
  
        <listitem>
         <para>
!         Ranks vectors based on the frequency of their matching lexems.
         </para>
        </listitem>
       </varlistentry>