static function toNFKD( $string ) {
		if ( NORMALIZE_INTL ) {
			return normalizer_normalize( $string, Normalizer::FORM_KD );
		} elseif ( preg_match( '/[\x80-\xff]/', $string ) ) {
			return self::NFKD( $string );
		} else {
			return $string;
		}
	}