[LEAPSECS] POSIX and C (Was: Re: ISO Influence)

Warner Losh imp at bsdimp.com
Fri Dec 24 18:35:18 EST 2010

On 12/24/2010 08:51, Rob Seaman wrote:

>> On Dec 23, 2010, at 5:45 PM, Jonathan E. Hardis wrote:


>>> WHERE under U.S. jurisdiction is UTC (no offset) the legal, civil time?

>> Cleaner answers still await, however.

> Well, a little googling tells us that "In Navy Cash, all dates and times are recorded and reported in Greenwich Mean Time (GMT) (Coordinated Universal Time (UTC))." (Repeated three times in the same document for emphasis.)


> However, one suspects that you're not talking about any of the military contexts given your emphasis on "legal" and "civil".


> ...but the conflation between GMT and UTC was too charming to resist coming from a U.S. Navy document :-)


> Commercial aircraft in flight? Sounds like a question for Patrick Smith...

When the US Navy uses GMT in its documents, it means UTC. It doesn't
mean the mean time near London... That's one of the problems with GMT:
it means different things to different people. NASA does the same
thing. It uses GMT to soothe the egos of their UK partners, but all
timing signals are sync to UTC.

This is why GMT is a meaningless phrase :).


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