The public keyring, indexes and help file from keys.pgp.net. This means that sites can poll for changes of the file simply by fetching the sum file and seeing if that has changed.
Sites can also check that the datafile has been transferred intact by checking the sum.
The files concerned are pubring.pgp , which is the keyring itself, and pubring.sum its checksum. His analysis was performed on the keys available at 1st January 1997. All revoked keys and signatures made by them have been ignored. For instance, those with distance 1 are signed by prz.acm.