<select> <optgroup label="Group 1"> <option>Option 1.1</option> </optgroup> <optgroup label="Group 2"> <option>Option 2.1</option> <option>Option 2.2</option> </optgroup> <optgroup label="Group 3" disabled> <option>Option 3.1</option> <option>Option 3.2</option> <option>Option 3.3</option> </optgroup> </select>