Abstract: A transactional system serves subscribers in a plurality of localities, and includes a national data base having a plurality of groups of addressed segments of data storage. Each group stores data pertaining to an associated locality, and each group is addressed by a locality number. There are provided a plurality of access-number addressed segments of data storage, and a device for linking the access-number addressed segments of data storage to the groups of locality-number addressed segments of data storage. At least one locality includes a plurality of sublocalities, and each locality number has a predetermined number of digits signifying the respective locality, and at least one additional digit for identifying the sub-locality; the latter may identify the zip code number. The groups of addressed segments of data storage preferably include classified ad sections.