So, the problem is a 64 bit int only gives you ~500 years around the epoch at nanosecond resolution. That's sufficient for timestamping, but not great for a gen

So, the problem is a 64 bit int only gives you ~500 years around the epoch at nanosecond resolution. That's sufficient for timestamping, but not great for a general purpose time library where even ordinary civil calculations might exceed that range, particularly in intermediate arithmetic. Since larger than 64 bit ints are a disaster for portability, the reasonable solution is to go with a 64 bit signed seconds, 32 bit nano offset field. A lot of language std libs have adopted something along these lines. DJB was advocating for everything to be in a format like this, referenced to TAI (UTC without leap seconds, basically). Sadly that didn't get any traction.