I think the base principles behind cleanups are great, and I intend proposing APNIC explore a similar course of action to the manual sweep. I am worried that there may be *external* referencees to objects, and while we have no 'contractual' obligation it might not be nice to do this to people without some engagement but I expect most people would welcome losing a path to spam. As to automatic sweeping, I think there are problems with link counting which are similar to those we've faced in discussing cross-database linkage and references. Too many risks of the link count getting out of whack. I think you could use it as a guide to a sweep, but not as a determinant without some review and other checks. Eg to trigger more exhaustive checks to see if there are are references in twisty ways. cheers -George