just got.)
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-singleline">
        <term><varname>SINGLELINE</varname></term>
        <listitem>
        <para>
        Setting this variable to <literal>on</literal> is equivalent to the command
        line option <option>-S</option>.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-singlestep">
        <term><varname>SINGLESTEP</varname></term>
        <listitem>
        <para>
        Setting this variable to <literal>on</literal> is equivalent to the command
        line option <option>-s</option>.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-sqlstate">
       <term><varname>SQLSTATE</varname></term>
       <listitem>
        <para>
         The error code (see <xref linkend="errcodes-appendix"/>) associated
         with the last SQL query's failure, or <literal>00000</literal> if it
         succeeded.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-user">
        <term><varname>USER</varname></term>
        <listitem>
        <para>
        The database user you are currently connected as. This is set
        every time you connect to a database (including program
        start-up), but can be changed or unset.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-verbosity">
        <term><varname>VERBOSITY</varname></term>
        <listitem>
        <para>
        This variable can be set to the values <literal>default</literal>,
        <literal>verbose</literal>, <literal>terse</literal>,
        or <literal>sqlstate</literal> to control the verbosity of error
        reports.
        (See also <command>\errverbose</command>, for use when you want a verbose
        version of the error you just got.)
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-version">
        <term><varname>VERSION</varname></term>
        <term><varname>VERSION_NAME</varname></term>
        <term><varname>VERSION_NUM</varname></term>
        <listitem>
        <para>
        These variables are set at program start-up to reflect
        <application>psql</application>'s version, respectively as a verbose string,
        a short string (e.g., <literal>9.6.2</literal>, <literal>10.1</literal>,
        or <literal>11beta1</literal>), and a number (e.g., <literal>90602</literal>
        or <literal>100001</literal>).  They can be changed or unset.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-variables-watch-interval">
        <term><varname>WATCH_INTERVAL</varname></term>
        <listitem>
        <para>
        This variable sets the default interval which <command>\watch</command>
        waits between executing the query.  Specifying an interval in the
        command overrides this variable.
        </para>
        </listitem>
      </varlistentry>

    </variablelist>

   </refsect3>

   <refsect3 id="app-psql-interpolation" xreflabel="SQL Interpolation">
    <title><acronym>SQL</acronym> Interpolation</title>

    <para>
    A key feature of <application>psql</application>
    variables is that you can substitute (<quote>interpolate</quote>)
    them into regular <acronym>SQL</acronym> statements, as well as the
    arguments of meta-commands.  Furthermore,
    <application>psql</application> provides facilities for
    ensuring that variable values used as SQL literals and identifiers are
    properly quoted.  The syntax for interpolating a value without
    any quoting is to prepend the variable name with a colon
    (<literal>:</literal>).  For example,
<programlisting>
testdb=&gt; <userinput>\set foo 'my_table'</userinput>
testdb=&gt; <userinput>SELECT * FROM :foo;</userinput>
</programlisting>
    would query the table <literal>my_table</literal>.