public function __construct($type)
{
if ($type != PelIfd::IFD0 && $type != PelIfd::IFD1 && $type != PelIfd::EXIF && $type != PelIfd::GPS && $type != PelIfd::INTEROPERABILITY) {
throw new PelIfdException('Unknown IFD type: %d', $type);
}
$this->type = $type;
}