Fields can appear in
      any order.  For each field there is the following:
     </para>

     <variablelist>
      <varlistentry>
       <term>Byte1</term>
       <listitem>
        <para>
         A code identifying the field type; if zero, this is
         the message terminator and no string follows.
         The presently defined field types are listed in
         <xref linkend="protocol-error-fields"/>.
         Since more field types might be added in future,
         frontends should silently ignore fields of unrecognized
         type.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>String</term>
       <listitem>
        <para>
         The field value.
        </para>
       </listitem>
      </varlistentry>
     </variablelist>
    </listitem>
   </varlistentry>

   <varlistentry id="protocol-message-formats-Execute">
    <term>Execute (F)</term>
    <listitem>
     <variablelist>
      <varlistentry>
       <term>Byte1('E')</term>
       <listitem>
        <para>
         Identifies the message as an Execute command.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32</term>
       <listitem>
        <para>
         Length of message contents in bytes, including self.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>String</term>
       <listitem>
        <para>
         The name of the portal to execute
         (an empty string selects the unnamed portal).
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32</term>
       <listitem>
        <para>
         Maximum number of rows to return, if portal contains
         a query that returns rows (ignored otherwise).  Zero
         denotes <quote>no limit</quote>.
        </para>
       </listitem>
      </varlistentry>
     </variablelist>
    </listitem>
   </varlistentry>

   <varlistentry id="protocol-message-formats-Flush">
    <term>Flush (F)</term>
    <listitem>
     <variablelist>
      <varlistentry>
       <term>Byte1('H')</term>
       <listitem>
        <para>
         Identifies the message as a Flush command.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32(4)</term>
       <listitem>
        <para>
         Length of message contents in bytes, including self.
        </para>
       </listitem>
      </varlistentry>
     </variablelist>
    </listitem>
   </varlistentry>

   <varlistentry id="protocol-message-formats-FunctionCall">
    <term>FunctionCall (F)</term>
    <listitem>
     <variablelist>
      <varlistentry>
       <term>Byte1('F')</term>
       <listitem>
        <para>
         Identifies the message as a function call.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32</term>
       <listitem>
        <para>
         Length of message contents in bytes, including self.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int32</term>
       <listitem>
        <para>
         Specifies the object ID of the function to call.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int16</term>
       <listitem>
        <para>
         The number of argument format codes that follow
         (denoted <replaceable>C</replaceable> below).
         This can be zero to indicate that there are no arguments
         or that the arguments all use the default format (text);
         or one, in which case the specified format code is applied
         to all arguments; or it can equal the actual number of
         arguments.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry>
       <term>Int16[<replaceable>C</replaceable>]</term>
       <listitem>
        <para>
         The argument format codes.  Each must presently be
         zero (text) or one (binary).
        </para>