Niall O'Reilly via db-wg wrote on 23/11/2022 18:17:
What I have in mind is AS-NIALLSPECIAL, which I populate with a list of AS numbers which I want to advertise to let others know that these are to be handled in some special way, unlike those in AS-NIALLNORMAL.
According to operational circumstances, there might be periods, even long ones, with nothing special going on; AS-NIALLSPECIAL would then be empty, but only for as long as this continued to be the case.
this ^^^ is one of the failure modes. It would not be safe to assume that empty as-sets named in RPSL policies are unused. It would be less unsafe to assume that unreferenced as-sets are unused. A reasonable middle ground might be - after the proposed new unqualified as-set block has been implemented - to check out all unreferenced as-sets older than a specific period of time and flag those for deletion. It would also be worthwhile inspecting rpsl in other IRRDBs to see if there are any references. The reason for this is that lots of people use tools like bgpq3 / peval / etc, and query aggregate IRRDBs, e.g. RADB, NTT, etc. So if you have RPSL in another IRRDB and this references an empty as-set in the RIPE IRRDB, that definition may be picked up in preference to other as-set definitions. I.e. by removing an as-set definition in the RIPE IRRDB, it could unexpectedly influence routing policies elsewhere. These are corner cases, but they should show why some care will be needed to figure out whether deleting these objects is a good idea. Nick