static function getUserCountryAttributeName( $requireUserCountry )
    {
        $ini = eZINI::instance( 'shop.ini' );
        if ( !$ini->hasVariable( 'VATSettings', 'UserCountryAttribute' ) )
        {
            if ( $requireUserCountry )
            {
                eZDebug::writeError( "Cannot find user country: please specify its attribute identifier " .
                                       "in the following setting: shop.ini.[VATSettings].UserCountryAttribute",
                                     __METHOD__ );
            }
            return null;
        }

        $countryAttributeName = $ini->variable( 'VATSettings', 'UserCountryAttribute' );
        if ( !$countryAttributeName )
        {
            if ( $requireUserCountry )
            {
                eZDebug::writeError( "Cannot find user country: empty attribute name specified " .
                                       "in the following setting: shop.ini.[VATSettings].UserCountryAttribute",
                                     __METHOD__ );
            }

            return null;
        }

        return $countryAttributeName;
    }