title: What is ToString("N0") format?
body: <p>This code is from Charles Pettzold's "Programming Windows Sixth Edition" book:</p>
  
  <pre><code>public object Convert(object value, Type targetType, object parameter, string language) 
  { 
      return ((double)value).ToString("N0"); 
  }
  </code></pre>
  
  <p><code>ToString("N0")</code> is supposed to print the value with comma separators and no decimal points. I cannot find the reference to appropriate <code>ToString</code> overload and <code>"N0"</code> format in the documentation. Please point me to the right place in .NET documentation.</p>