A Geo disc is typically purchased at the same time as a ZP4 disc. ZP4 can be purchased without a Geo disc, but purchasing a Geo disc requires purchasing the corresponding ZP4 disc (Geo lookups require ZP4).
A Geo CD-ROM is released every month, for use with a corresponding ZP4 edition. Once Geo data is installed, ZP4 is able to automatically determine latitudes and longitudes, and Census Bureau tract and block numbers, for any ZIP + 4 code in the Geo database. Reverse lookups, such as finding ZIP + 4 records for a latitude and longitude, can also be performed. The Geo database is rebuilt monthly from Census Bureau Tiger 2006 Second Edition address files. If an address is not listed in the Tiger database, the address will not be included in the Geo database.
Geo lookups may not be performed after the 30-day expiration date of the Geo database. Once a Geo database expires, you must purchase a current Geo database, and the corresponding ZP4 edition, to continue performing Geo lookups.