/// <summary>
/// Gets an enumerator for enumerating through the content
/// descriptors.
/// </summary>
/// <returns>
/// A <see cref="T:System.Collections.IEnumerator`1" /> for
/// enumerating through the content descriptors.
/// </returns>
public IEnumerator <ContentDescriptor> GetEnumerator()
{
return(ext_description.GetEnumerator());
}