Как в запросе заменить wm_concat на listagg?

Никак не могу удачно заменить wmsys.wm_concat на wmsys.listagg.

select 
  '.' || wmsys.wm_concat(A.description) as EXPR 
from 
  (
    select 
      distinct 1 as "Z", 
      server_name || '.' || func_name as description 
    from 
      reglament 
    where 
      record_status in (3, 4) 
      and (
        mstype_current <> 0 
        or upper(message) like '%ALERT%' 
        or upper(message) like '%ERROR%' 
        or upper(message) like '%ODBC%' 
        or upper(message) like '%REPAIR%'
      ) 
      and filial_id = 1111 
    UNION 
    select 
      B.X + B.Y + B.W as "Z", 
      B.description 
    from 
      (
        select 
          distinct case when ALERT_PERIOD - (
            LAST_PROCESSING_DATE - LAST_PROCESSING_DATE_OK
          ) 243600 < 0 
          and stype = 4 
          and SERVER_NAME not like 'CDBFUNC' then '1' else '0' end as "X", 
          case when ALERT_PERIOD - (
            LAST_PROCESSING_DATE - LAST_PROCESSING_DATE_OK
          ) 243600 < 0 
          and stype = 4 
          and SERVER_NAME like 'CDBFUNC' then '1' else '0' end as "W", 
          case when ALERT_PERIOD /(24 * 3600) - (
            LAST_PROCESSING_DATE - LAST_PROCESSING_DATE_OK
          ) < 0 
          and stype in (5, 6) then '1' else '0' end as "Y", 
          server_name || '.' || func_name as description 
        from 
          reglament 
        where 
          record_status in (3, 4) 
          and ALERT_ERRRESULT = '1' 
          and filial_id = 1111
      ) B
  ) A 
where 
  A.Z = 1
);