On Thu, 14 Aug 2008, Steve Allen wrote: > I also maintain that the "right" forms of the zoneinfo files already > are proof of concept. They demonstrate that computers can have an > uniform underlying time scale while still providing a civil time scale > that has leap seconds. The technical issues are basically solved.
As a proof of concept they tell us what *not* to do in any proper solution for transmitting both civil time and uniform time. In particular, do *not* change the exported interpretation of past timestamps. (For example, past POSIX timestamps stored in filesystems should remain interpreted as UTC according to the POSIX formula.) As I said in my message of 11 February: The question does not relate to the *correctness* of those timestamps, it's a case where consistency is much more important than correctness. If a system has a timestamp and exports an interpretation of that timestamp, and another system stores that interpretation or a second timestamp derived from it, and then one system changes its interpretation, the timestamps are no longer in sync between the two systems. This can cause issues such as unnecessary remirroring of very large amounts of data whose timestamps no longer match at the two ends. See http://lists.debian.org/debian-user/1997/03/msg00075.html for an example of this from when Debian made the mistake of trying to go it alone with a different interpretation of timestamps. There are further discussions in the debian-devel archives from March-May 1997 of things that broke. If you do not change the timestamp interpretation formula in POSIX, but stop inserting leap seconds at some point (or define that timestamps after that point are in TI not UTC), you can avoid the issue of reinterpreting existing timestamps. So maybe something like "right", but only with a smooth transition from UTC to uniform time at some point well in the future. -- Joseph S. Myers [EMAIL PROTECTED] _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
