<para>
             The lowest <literal>catalog_xmin</literal> of any replication
             slots on the standby. Set to 0 if no <literal>catalog_xmin</literal>
             exists on the standby or if hot standby feedback is being
             disabled.
            </para>
           </listitem>
          </varlistentry>

          <varlistentry>
           <term>Int32</term>
           <listitem>
            <para>
             The epoch of the <literal>catalog_xmin</literal> xid on the standby.
            </para>
           </listitem>
          </varlistentry>
         </variablelist>
        </listitem>
       </varlistentry>
      </variablelist>
     </listitem>
    </varlistentry>

    <varlistentry id="protocol-replication-start-replication-slot-logical">
     <term><literal>START_REPLICATION</literal> <literal>SLOT</literal> <replaceable class="parameter">slot_name</replaceable> <literal>LOGICAL</literal> <replaceable class="parameter">XXX/XXX</replaceable> [ ( <replaceable>option_name</replaceable> [ <replaceable>option_value</replaceable> ] [, ...] ) ]</term>
     <listitem>
      <para>
       Instructs server to start streaming WAL for logical replication,
       starting at either WAL location <replaceable
       class="parameter">XXX/XXX</replaceable> or the slot's
       <literal>confirmed_flush_lsn</literal> (see <xref
       linkend="view-pg-replication-slots"/>), whichever is greater. This
       behavior makes it easier for clients to avoid updating their local LSN
       status when there is no data to process. However, starting at a
       different LSN than requested might not catch certain kinds of client
       errors; so the client may wish to check that
       <literal>confirmed_flush_lsn</literal> matches its expectations before
       issuing <literal>START_REPLICATION</literal>.
      </para>

      <para>
       The server can reply with an error, for example if the
       slot does not exist. On success, the server responds with a CopyBothResponse
       message, and then starts to stream WAL to the frontend.
      </para>

      <para>
       The messages inside the CopyBothResponse messages are of the same format
       documented for <literal>START_REPLICATION ... PHYSICAL</literal>, including
       two CommandComplete messages.
      </para>

      <para>
       The output plugin associated with the selected slot is used
       to process the output for streaming.
      </para>

      <variablelist>
       <varlistentry>
        <term><literal>SLOT</literal> <replaceable class="parameter">slot_name</replaceable></term>
        <listitem>
         <para>
          The name of the slot to stream changes from. This parameter is required,
          and must correspond to an existing logical replication slot created
          with <literal>CREATE_REPLICATION_SLOT</literal> in
          <literal>LOGICAL</literal> mode.
         </para>
        </listitem>
       </varlistentry>

       <varlistentry>
        <term><replaceable class="parameter">XXX/XXX</replaceable></term>
        <listitem>
         <para>
          The WAL location to begin streaming at.
         </para>
        </listitem>
       </varlistentry>

       <varlistentry>
        <term><replaceable class="parameter">option_name</replaceable></term>
        <listitem>
         <para>
          The name of an option passed to the slot's logical decoding output
          plugin.  See <xref linkend="protocol-logical-replication"/> for
          options that are accepted by the standard (<literal>pgoutput</literal>)
          plugin.
         </para>
        </listitem>
       </varlistentry>

       <varlistentry>
        <term><replaceable class="parameter">option_value</replaceable></term>
        <listitem>
         <para>
          Optional value, in the form of a string constant, associated with the
          specified option.
         </para>
        </listitem>
       </varlistentry>
      </variablelist>