public function setCode( $key )
	{
		if ( $key == $this->getCode() ) { return; }

		if ( strlen($key) != 3 || ctype_alpha( $key ) === false ) {
			throw new MShop_Locale_Exception( sprintf( 'Invalid characters in ISO currency code "%1$s"', $key ) );
		}

		$this->_values['code'] = strtoupper( $key );
		$this->_modified = true;
	}