Both Geonames and other multinational features have two numeric identifiers. Geonames features have a unique feature identifier (UFI) and a unique name identifier (UNI), and Geoname-compliant features have a named feature identifier (NFI) and a name identifier (NFN). The UFI and UNI are linked to the GeoNames table, which contains feature names, as well as information about naming conventions, that apply across all the countries that use Geoname-compliant product specifications. These product specifications include GIFD, MGCP, VM2T_D4, and VMap2TLM.
Linking compliant features with the GeoNames table is a two-step process. First, a Geonames feature must be associated with a compliant feature, which happens once the UFI and UNI are copied into the NFI and NFN fields for a selected feature. To do this, select one Geonames feature and at least one compliant feature with which to associate it, then click the Geonames UFI2NFI button. Once that is done, the UFI is used to populate the compliant feature's name using the GeoNames table. The Geonames Update tool searches for the UFI in the GeoNames table and populates the compliant feature's NAM field with the appropriate feature name.