A geofeed is a plain CSV file a network operator publishes to declare where its own IP prefixes are, one line per prefix with a country, a region and a city, in the format RFC 8805 fixed in 2020. The registries let an operator point at its file from the registration record of its address space, so anyone reading the registry can find the operator's own answer instead of inferring one from measurements.
What Spaw answers
Where a geofeed or an operator's own list covers an address, its declaration wins over the database and location_source reads operator; location_confidence is then high, because the network operator said so, unless the address is anycast or sits on a listed mobile carrier or satellite operator: there the declared place is a gateway, an anycast instance or a ground station, and the grade is low. The service discovers every geofeed the five registries point at once a week and compiles them into one feed, beside the provider lists it reads directly (Apple's relay egress file, the server lists of the VPN providers, the cloud providers' RFC 8805 files). When an operator's declaration disagrees with the database on the country or the city, the region and the coordinates answer null rather than a point in the wrong place.
What it does not mean
A geofeed is a statement, not a measurement: it is as accurate as the operator keeps it, and it describes where a prefix is deployed, not where a particular subscriber sits inside a city. Most consumer ISPs publish none, which is why the database, and the weekly measurement against the geofeeds that do exist, still carry most addresses.