Re: [Tzdist] Fwd: [tzdist] #32 (service): managing historical data

[Lester Caine <[e-mail]>]

On 11/12/14 20:19, Doug Royer wrote:
>> Calendaring systems still do not cover cross timezone activities well,
>> and I don't think iCalendar is particularly friendly in solving the
>> problems that need to be handled? For genealogical data we often flag
>> a time range covering the uncertainty in when an event happened so
>> that when time lining events one can see if something could have been
>> concurrent which can then can be researched in further detail. While
>> planning new events where a site may have a variation of local offset
>> it would be useful that the tzdist data actually flagged that there is
>> uncertainty in a forthcoming event if only to allow an organiser to
>> block bookings on that day or period. Often the organisers have no
>> understanding that these events may happen, so in addition to cleanly
>> publishing a short notice change, publishing a potential race problem
>> is an equally valid objective? 
> 
> Is that not what BUSY-TENTATIVE is used for?
> Or maybe PARTSTAT=TENTATIVE or STATUS=TENTATIVE ?
> It would have to be up to the CUA/user/organizer to decide if they want
> to book one of those times.

I don't use iCalendar which is why I would prefer a clean TZ dataset
rather than one that is processed to what I still view as a non-standard
format for other calendaring systems. So I'm looking at the information
being transferred rather than a single usage. So I'd welcome any input
on just how some of these things could be presented.

> As to TZ data, are you saying 'it may have been this time range' with
> respect to past time zone entries?
For the historic material that is currently relegated to backzone that
may well be the case, but for current data TZ publishes the 'best guess'
for the next transition on many TZid's and the notes advise what event
may change that guess. I've covered this some time back in that we could
add comments to an offset to indicate that a transition may change at
short notice. Currently there is no mechanism in TZ to flag that there
are two potential values for a period but it is something that at the
calendaring level would be useful to display.

-- 
Lester Caine - G8HFL
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