data type name, and
    constraint name are supplied only for a limited number of error types;
    see <xref linkend="errcodes-appendix"/>.  Frontends should not assume that
    the presence of any of these fields guarantees the presence of another
    field.  Core error sources observe the interrelationships noted above, but
    user-defined functions may use these fields in other ways.  In the same
    vein, clients should not assume that these fields denote contemporary
    objects in the current database.
   </para>
  </note>

  <para>
   The client is responsible for formatting displayed information to meet its
   needs; in particular it should break long lines as needed.  Newline characters
   appearing in the error message fields should be treated as paragraph breaks,
   not line breaks.
  </para>
 </sect1>

 <sect1 id="protocol-logicalrep-message-formats">
  <title>Logical Replication Message Formats</title>

  <para>
   This section describes the detailed format of each logical replication
   message.  These messages are either returned by the replication slot SQL
   interface or are sent by a walsender.  In the case of a walsender, they are
   encapsulated inside replication protocol WAL messages as described in
   <xref linkend="protocol-replication"/>, and generally obey the same message
   flow as physical replication.
  </para>

  <variablelist>
   <varlistentry id="protocol-logicalrep-message-formats-Begin">
    <term>Begin</term>
    <listitem>
     <variablelist>
      <varlistentry>
       <term>Byte1('B')</term>
       <listitem>
        <para>
         Identifies the message as a begin message.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int64 (XLogRecPtr)</term>
       <listitem>
        <para>
         The final LSN of the transaction.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int64 (TimestampTz)</term>
       <listitem>
        <para>
         Commit timestamp of the transaction. The value is in number
         of microseconds since PostgreSQL epoch (2000-01-01).
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32 (TransactionId)</term>
       <listitem>
        <para>
         Xid of the transaction.
        </para>
       </listitem>
      </varlistentry>
     </variablelist>
    </listitem>
   </varlistentry>

   <varlistentry id="protocol-logicalrep-message-formats-Message">
    <term>Message</term>
    <listitem>
     <variablelist>
      <varlistentry>
       <term>Byte1('M')</term>
       <listitem>
        <para>
         Identifies the message as a logical decoding message.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32 (TransactionId)</term>
       <listitem>
        <para>
         Xid of the transaction (only present for streamed transactions).
         This field is available since protocol version 2.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int8</term>
       <listitem>
        <para>
         Flags; Either 0 for no flags or 1 if the logical decoding
         message is transactional.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int64 (XLogRecPtr)</term>
       <listitem>
        <para>
         The LSN of the logical decoding message.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>String</term>
       <listitem>
        <para>
         The prefix of the logical decoding message.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32</term>
       <listitem>
        <para>
         Length of the content.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Byte<replaceable>n</replaceable></term>
       <listitem>
        <para>
         The content of the logical decoding message.