Basic rationale of the KEP #2 design

Bernhard Reiter bernhard at
Thu Mar 3 12:10:03 CET 2011

Am Mittwoch, 2. März 2011 18:34:53 schrieb Joon Radley:
> The only true use case proven was in recurring items where the originators
> recurring appointment time in his time zone must stay the same during the
> switch between standard and day light savings time.

A second use case was, the change of the timezone definitions over longer 
periods of time.

A third use case is that some client would like to enable users to display
a datetime in a specific timezone and would like to save the timezone
with the field, so it can be brought up in the way the user selected it.

I believe all three use cases are valid.

> We cannot modify the Outlook GUI to enforce this and can only attempt to
> hack a solution in the storage format. This will result in incompatibility
> between clients.

I agree that there should be no need for Outlook to change the GUI.
The only requirement I found which could have such an effect is
"Clients MUST default to the information in the stored time zone when opening 
an event for editing"
It would be a problem if "default to the information" means displaying 
the saved timezone. Maybe a SHOULD is enough here, as it would force all 
clients to display this, if they can.

> Also changing the entire formats date time formatting and paring based on
> rather small use case is not a good idea. Introduce the zone in the
> recurring object where the use case is.

The other two use cases are valid as well. 
Maybe a bit less important, but still valid.
Therefor if the client can interpret the tz id nicely in the recurrent case,
the code is there and it can interpret it in the other cases.

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