WTF?

private const FileOptions requiredOptions =
FileOptions.Asynchronous | FileOptions.DeleteOnClose | FileOptions.Encrypted |
FileOptions.RandomAccess | FileOptions.SequentialScan | FileOptions.WriteThrough;

private void someMethod(FileOptions options)

{

if ((options & ~requiredOptions) != FileOptions.None)

throw new ArgumentOutOfRangeException("options");

}