
      a <a href="../../../../format/index.html" target="_top">Boost.Format</a> recognised format
      specifier: the argument <code class="computeroutput"><span class="identifier">val</span></code>
      is inserted into the error message according to the specifier used.
    </p>
<p>
      For example if <code class="computeroutput"><span class="identifier">Message</span></code> contains
      a "%1%" then it is replaced by the value of <code class="computeroutput"><span class="identifier">val</span></cod