title: What is proper RegEx expression for SWIFT codes?
body: <p>I have to filter user input to on my web ASP.NET page:</p>
  
  <pre><code>&lt;asp:TextBox runat="server" ID="recipientBankIDTextBox" MaxLength="11" /&gt;
  &lt;asp:RegularExpressionValidator runat="server" ValidationExpression="?" ControlToValidate="recipientBankIDTextBox" ErrorMessage="*" /&gt;
  </code></pre>
  
  <p>As far is I know SWIFT code must contain 5 or 6 letters and other symbols up to total length 11 are alphanumeric.</p>
  
  <p>How to implement such rule properly? </p>