Re: RFC 2445 Q: is TZID broken?

[John Stracke <jstracke@xxxxxxxxxxx>]

On Wed, 2003-01-22 at 13:48, Mark Swanson wrote:

    Since I'm seeing various popular ICalendar implementations use their
    own 
    formats, how can anything be expected to interoperate?

>From section 4.2.19 of RFC-2445:

    An individual "VTIMEZONE" calendar
       component MUST be specified for each unique "TZID" parameter
    value
       specified in the iCalendar object.

In other words, even if a TZID starts with a "/", and so is nominally
global, its scope is still local to the VCALENDAR.

    You obviously can not rely on GMT offset ("America/Phoenix" and 
    "America/Denver" both have GMT-07:00, but differ in daylight savings
    behavior) so time zone identifiers are required.

Global time zone identifiers are nearly impossible; at a minimum, they
would have to come with a timestamp, since time zone definitions change
over time.

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