[LEAPSECS] Time math libraries, UTC to TAI

[Warner Losh]

> I agree that POSIX defines its own time scale for time_t, but that is
> not how it is being used.  Everyone sets their computer’s clock to UTC,
> no matter what the standard says, and no matter how many seconds have
> passed since 1970-01-01T00:00:00Z.

I think that POSIX has de-facto redefined UTC, and it's time that the
UTC standard catch up to this quiet revolution. Standards are
important, but UTC isn't sacrosanct, nor is DUT1 < 0.9s. When they
took a pass at defining a model that reflected reality, the
pervasiveness of time_t has effectively redefined UTC. It's too late
to redefine the standard, or define a new standard to use: that ship
sailed sometime in the 80's.

Warner