See [geourl.org...] for some details. As far as I know, the so-called "ICBM" system is a holdover from Usenet days, and is not commonly valued outside specific databaase projects such as GeoURL that I linked to. There are other systems more commonly in use today, for example, in geo-tagging a photo.

It sounds like you are working on some kind of Local Search project - you may find more specific help in our Local Search forum [webmasterworld.com]