ietf-nntp Section 11.5 - NEWNEWS

[Paul Overell]

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In article <ylaeazmy6f.fsf at windlord.stanford.edu>, Russ Allbery
<rra at stanford.edu> writes
>Paul Overell <paulo at turnpike.com> writes:
>> Clive D.W. Feather <clive at demon.net> writes
>
>
>>> + The server is not required to track leap seconds or UT/TAI/UTC
>>> + variations exactly, nor need the server's clock be accurate to within
>>> + 1 second.
>
>As long as it's clear that if the server is actually keeping TAI, the news
>server software isn't required to convert that to UTC.  We don't want to
>go there, and it's very reasonable (and more useful for some applications)
>to set a Unix system clock to track TAI instead of UTC.  I know quite a
>few people who do so.
>

The system can run its internal clock anyway it wants to, and I know
that TAI is sometimes used (Olson's time library, Dan Bernstein's TAI
library etc).  However, for NNTP the date and time delivered by the DATE
command MUST be in UTC, not TAI.

>> I think invoking UT/TAI/UTC/ is muddying the waters.  It's in UTC (not
>> UT, not TAI, not POSIX).  Saying what accuracy is not required doesn't
>> say what accuracy is required.  I suggest:
>
>>         The date and time are given in UTC.  The date and time SHOULD be
>>         accurate.
>
>> Using "SHOULD" gives the server the get-out if they can't support leap
>> seconds or if their clock drifts a bit, but if they can get it right
>> then they SHOULD.
>
>Yeah, but you're implying to the client author more accuracy than may be
>there; if the server is actually keeping TAI, the clock could easily be
>off from UTC by half a minute or more.
>

To return TAI when UTC is specified is not a lack of accuracy, it is
broken.

We are specifying the NNTP protocol not system clock architecture or
time conversion algorithms.  The date and time response is in UTC, how
the server achieves this is beyond our scope.


Regards
- -- 
Paul Overell                                             T U R N P I K E

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