On Mon, Feb 22, 2010 at 6:50 PM, Daniel Ruoso <dan...@ruoso.com> wrote: > So why have the duration TAI-based? > > Simply because TAI is supposedly immutable as a scale, so it's predictable. > Gregorian time is not immutable and timezone definitions are not anyhow > predictable.
OK, this seems to be a point of confusion. TAI *is defined in terms of the Gregorian calendar*. It is not just a sequence of anonymous seconds ticking off at the rate specified by SI. TAI specifies a name for each second, not just the amount of time between them. And that name is a date/time using the Gregorian calendar. If you like, you can convert it to a Julian Date, but that's a one-to-one mapping. You're still going to get a value that's wrong for civil purposes - that is, currently 34 seconds fast compared to an NTP-synchronized clock. If Perl's internal idea of time is just a count of atomic seconds, great. That, however, is not TAI. UTC and TAI and the proposed leap-second-free UTC-replacement "TI" all tick at the same rate and at the same time, and you can devise any number of time scales that do likewise, differing only in the labels. -- Mark J. Reed <markjr...@gmail.com>