A while ago I vaguely remember a prediction on this list of when the TZif file format will become obsolete because we have accumulated 2**31 total leap seconds if we continue to just add leap seconds as needed to keep UTC roughly in sync with TAI. To some extent this is just a playful prediction, as the format will undoubtedly become obsolete for other reasons long before then, but it's still fun to predict. Unfortunately I don't remember the details, and a quick Google search didn't find it. Does anyone else remember this? If not, I'll have to recalculate. The topic has just come up again on the tzdist-bis mailing list, which is why I'm thinking about it again. See <https://mailarchive.ietf.org/arch/msg/tzdist-bis/Q7OVmd60wydqcJahS3QRNHwtXHM>.