KEP 2: Modification of datetime type, introduction of 'tz' sub-tag
Georg C. F. Greve
greve at kolabsys.com
Wed Nov 17 14:58:08 CET 2010
On Wednesday 17 November 2010 14.04:07 Hendrik Helwich wrote:
> is the second example a valid kolab datetime value? Referring to  only
> the first example should be valid. But both forms hold the same
> information so this is not a problem but maybe a small inconsistency with
> the kolab format specification.
You are right, of course.
But both are examples of timestamps in real existing files I have here.
As both provide Zulu time, but express it differently, the risk is probably
minimal. But yes, you are right, the format document says that only the first
is valid while this was written by a reference implementation, which the
format document also says demonstrates correct behaviour.
So it is an inconsistency, and a reason why I believe we should link this to
the RFC that everyone else is using for this purpose, as all the operating
systems that are network capable have built-in functions to read and write
> Where are DST information stored? Is this information read from an
> external source or is it stored inside the kolab format?
DST information should not be stored in the format, because it is subject to
change. But all operating systems that are capable of running Kolab clients
have timezone information and libraries available which can provide this
mapping, and are kept up to date by the distributions themselves, so changes
would be handled correctly in the future.
The referenced Olson database seems the best and most canonical resource for
this across all systems that we could find. It is certainly present on all
GNU/Linux systems, which are the ones that Evolution would be running on.
On my Fedora system, it is located at /usr/share/zoneinfo/zone.tab.
Georg C. F. Greve
Chief Executive Officer
Kolab Systems AG
e: greve at kolabsys.com
t: +41 78 904 43 33
pgp: 86574ACA Georg C. F. Greve
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