TYPO3 v4.6 Questions about RealUrl (nomatch for lookuptable) - content-management-system

Question

You must get a reference to the type:
http://site.ru/agencies/town/name_agencies.
Here is an example of code that is at the moment:
'fixedPostVars' => array(
'71' => array (
array (
'GETvar' => 'tx_extention_pi1[town_id]',
'lookUpTable' => array(
'table' => 'tx_extention_table',
'id_field' => 'uid',
'alias_field' => 'town_name',
'addWhereClause' => ' AND NOT deleted',
'useUniqueCache' => 1,
'useUniqueCache_conf' => array(
'strtolower' => 1,
'spaceCharacter' => '-',
),
),
),
array (
'GETvar' => 'tx_extention_pi1[uid]',
'lookUpTable' => array(
'table' => 'tx_extention_table2',
'id_field' => 'uid',
'alias_field' => 'IFNULL(NULLIF(pathsegment,""), agency_title)',
'addWhereClause' => ' AND NOT deleted',
'useUniqueCache' => 1,
'useUniqueCache_conf' => array(
'strtolower' => 1,
'spaceCharacter' => '-',
),
),
),
),
),
The result of his work is correct, but taking into account the fact that town_id always determined.
If town_id not established a link have the form:
site.ru/agencies//name_agencies
And the need for such a case:
site.ru/agencies/name_agencies
Use 'noMatch' => 'bypass' makes no sense, since it is intended to 'valueMap' => array (). A 'valueDefault' => 'string' only specifies the default option, unless otherwise provided.
Is there any option that is designed to 'lookUpTable' => array (), but to work as a 'noMatch' => 'bypass'?
I.e. to move to the next segment if the current is not defined.