On Fri, Nov 4, 2011 at 4:02 PM, Steve Allen <sla@ucolick.org> wrote:
On Fri 2011-11-04T19:39:04 +0000, Zefram hath writ:
In a couple of months, a decision is going to be made about possibly ceasing leap seconds in UTC. If that happens, the tz database is going to be thrown into a world of hurt, as "UTC = GMT" gradually ceases to be a viable approximation.
My prediction is that the above will not happen (assuming the change goes through) as - GMT doesn't really exist as a separate time standard - most people will not notice or care that UTC is drifting off from UT1 - the people doing really precise navigation already use UT1 and have for years I would be surprised if any lawmaker ever paid any attention to this change. In order( 2000 years), when we need a leap hour, things may be different. Regards Marshall
The existing tzcode has most of the complexity needed to handle the situation using the information in the "leapseconds" file, with a caveat below about authority.
The bigger problem will lie in trying to infer whether the laws and practices of some jurisdictions mean that they want "new UTC" (purely atomic) or "old UTC" (< 1s approximation to GMT). Since the law and policy makers themselves are generally unaware of the distinction, this may take some time to sort out. Islamic nations might tend to choose to stay with earth rotation.
The authority problem lies in whether or not the IERS would interpret their charter as calling for them to continue to issue leap second announcments of the sort currently encoded in the "leapseconds" file for the sake of those countries whose civil time is explicitly based on GMT as opposed to UTC. In the absence of the single authority currently in the IERS it could be that multiple authorities would start pronouncing when their jurisdictions should implement a leap. That would be a world of hurt.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m