"></div>
                      <div class="abstract">
                        <p><code>ISBNRule</code> is a subclass of <code><a href="Protocols/Rule.html">Rule</a></code>. It is used to verify whether a field is a valid ISBN number.</p>

                        <a href="Classes/ISBNRule.html" class="slightly-smaller">See more</a>
                      </div>
                      <div class="declaration">
                        <h4>Declaration</h4>
                        <div class="language">
          