Dates: TAI64, TAI or UTC? about biscuit

[Geal]

right, I think what happened here is that I intended to use TAI64 (I recall some discussions around it early in spec development), but for all implementations we went with Unix timestamps. I just checked, and Rust, Java, Go and Haskell all use it, so we should update the spec to indicate a Unix timestamp

[arnsholt]

Yeah, that happens. But if it's a timestamp maybe the proto schema type should also change to an int64 rather than a uint? I mean, not being able to represent dates prior to 1970 is probably fine practically, given the typical uses of a biscuit, but it still feels incomplete. And given a signed 64 bit signed int and second resolution, the furthest date into the future that can be represented is still almost 300 billion years ahead, which really should be enough for everyone.