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Re: [MMUSIC] RFC 4566bis - issue 7 - clarification
On Jul 15 2008, at 14:28, Magnus Westerlund wrote:
Does anyone understand appendix E of RFC 1305 well enough to
comment? I'm not sure this change is correct, but equally it's not
clear that the current text is right either.
http://ftp.arnes.si/standards/rfc/rfc1305.pdf starting on page 70
(you need the PDF version of this RFC...)
In reality this likely hasn't been a problem as both NTP and Unix
time uses UTC as base, but to be clear adding that is probably fine.
What I really wonder is how correct the "To convert these ..." is
due to the leap seconds. To my understanding Unix times uses a
definition that a day always is 86400 seconds. While to my
understanding the NTP timestamp will contain the leap seconds. And
if NTP timestamps are to be converted into UTC time year, day, hour
and second then they need to be taken into account. Thus a simple
subtraction will be giving the wrong time.
You might be able to solve the problem by not trying to (re-)define
the NTP time scale, so I think this change goes exactly in the wrong
direction. The information about 1900 could go into a note instead,
as well as the helpful sentence about subtracting 2208988800 to get a
time scale that most engineers think they understand. Both should stay
there, as they are pretty much true, and could be supplemented by
mentioning UTC somewhere. In the note.
(The 2208988800 may not be exactly true to fractional values,
depending on your definition of "UNIX time", which might mean the
strange beast "POSIX.1 system time" and then suddenly become way more
complex in the vicinity of leap seconds, but nobody will care in the
context of this standard.)
Gruesse, Carsten
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