diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index 09e6dfc..e3d1c62
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** local0.*    /var/log/postgresql
*** 3667,3672 ****
--- 3667,3673 ----
          cluster data directory.
          This parameter can only be set in the <filename>postgresql.conf</>
          file or on the server command line.
+         The default is <literal>pg_log</literal>.
         </para>
        </listitem>
       </varlistentry>
*************** local0.*    /var/log/postgresql
*** 3693,3698 ****
--- 3694,3700 ----
          </ulink> specification.
          Note that the system's <systemitem>strftime</systemitem> is not used
          directly, so platform-specific (nonstandard) extensions do not work.
+         The default is <literal>postgresql-%Y-%m-%d_%H%M%S.log</literal>.
         </para>
         <para>
          If you specify a file name without escapes, you should plan to
*************** local0.*    /var/log/postgresql
*** 3709,3716 ****
          log file name to create the file name for CSV-format output.
          (If <varname>log_filename</> ends in <literal>.log</>, the suffix is
          replaced instead.)
-         In the case of the example above, the CSV
-         file name will be <literal>server_log.1093827753.csv</literal>.
         </para>
         <para>
          This parameter can only be set in the <filename>postgresql.conf</>
--- 3711,3716 ----