Hello Congwu, On Mar 4, 2010, at 9:04 , Chen Congwu wrote:
> I am a bit confused about timezone handling in vcalendar 1.0 format, if I > have a VEVENT with a local timezone say 'Asia/Shanghai', how does it expressed > in DTSTART field? libsynthesis uses UTC for all points in time, because then even if the time zone detection does not work, at least the point in time will usually be correct (unless it's something as complex as a recurrence over DST boundaries). As far as I remember, all phone clients I saw use UTC as well (except for very old ones which have a localtime-only calendar, and can't do any time zone calculations). > In icalendar 2.0, there is a parameter 'TZID' for DTSTART, so I can add it > there, > in vcalendar 1.0, how does it supposed to work? Will it use the item level > 'TZ' > property? I suspect so. Yes, that's how it works. But as TZ/DAYLIGHT support is something rarely found working correctly (or implemented at all), I'd always use UTC and treat the TZ information as a nice supplementary information, if present. If no TZ is there, the item time zone defaults to the user time zone. > What I found with libsynthesis/SyncEvolution is it always send time in UTC > format with absolution timezone if remote can handle UTC. (While in icalendar > we > will send time in UTC format with timezone specified by 'TZID' parameter). > This > does not have negative effect but I am curious whether the different handling > is > intentional? Yes, definitely :-) Best Regards, Lukas Zeller ([email protected]) - Synthesis AG, SyncML Solutions & Sustainable Software Concepts [email protected], http://www.synthesis.ch _______________________________________________ os-libsynthesis mailing list [email protected] http://lists.synthesis.ch/mailman/listinfo/os-libsynthesis
