[LEAPSECS] An example
imp at bsdimp.com
Tue Nov 2 17:03:49 EDT 2010
On 11/02/2010 14:38, Poul-Henning Kamp wrote:
> In message<20101102202753.GC21438 at ucolick.org>, Steve Allen writes:
>> On Tue 2010-11-02T20:22:29 +0000, Poul-Henning Kamp hath writ:
>>> It admits no such thing, and for all I know, and despite your
>>> complaints about the lack of an "essen" unit, that there is more
>>> than one definition of a second in use at present ?
>> Section A.4.15
>> "Note that as a practical consequence of this, the length of a
>> second as measured by some external standard is not specified."
>> Is this not the POSIX standard?
> Technically it is not, it is the Open Group standard, but that's not
> There is a difference between "not specified" and "different from".
> I know of no compliant system, where seconds are not SI-second length
> to the best of the ability of the hardware and software.
> If you want to carry this point, please quote actual system documentation
> that specifies a goal of having seconds different from SI seconds.
Especially in light of:
"the value is related to a Coordinated Universal Time name ..."
which explicitly invokes UTC, which ticks explicitly in SI seconds.
Those statements, imho, are there to decline to set a maximum error
between the time the system thinks it is, and the time that NIST or some
other national body thinks it is. A standards compliant system could be
345 seconds different than the time NIST publishes via their NTP
servers. A standards compliant system could also be off by 12us. The
application programmer has no way of knowing that error and shouldn't
rely on it being smaller than any specific amount.
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