is not possible to nest the optgroup element, so only one level of grouping can be done within a select.</p>
      <p>If grouping information is essential to understanding the list, authors may define option labels that can be understood even when the screen reader does not present the grouping information provided by optgroup.</p>
   </section><section class="examples"><h2>Examples</h2>
      <section class="example">
         <section class="description"><h2>Description</h2>
            <p>The following c