for::getExternalId

static function getExternalId($locationId)
{
	if($locationId == '')
		return '';

	$srvId = static::getExternalServiceId();

	if($srvId <= 0)
		return 0;

	$res = LocationTable::getList(array(
		'filter' => array(
			array(
				'LOGIC' => 'OR',
				'=CODE' => $locationId,
				'=ID' => $locationId
			),
			'=EXTERNAL.SERVICE_ID' => $srvId
		),
		'select' => array(
			'ID', 'CODE',
			'XML_ID' => 'EXTERNAL.XML_ID'
		)
	));

	$result = '';

	if($loc = $res->fetch())
		$result = $loc['XML_ID'];

	if($result == '')
		$result = self::getUpperCityExternalId($locationId, $srvId);

	return $result;
}