Subject: [Ietf-calsify] All Day Events and DTEND

From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Mon Feb 5 10:16:39 2007

I just realized that the 1st issue is already being tracked as issue 10
in the tracker.

http://www.ofcourseimright.com/cgi-bin/roundup/calsify/issue10

Cheers,
Bernard

Bernard Desruisseaux wrote:
> Eliot,
> 
> There are two issues here:
> 
> 1- Handling of DTEND for day events;
> 2- Default duration of day events.
> 
> The 1st issue was brought up on the list in October 2005 by Chris Stoner:
> 
> http://lists.osafoundation.org/pipermail/ietf-calsify/2005-October/000821.html 
> 
> 
> and I was under the impression that concensus was reached back then.
> Check Reinhold's replies:
> 
> http://lists.osafoundation.org/pipermail/ietf-calsify/2005-October/000823.html 
> 
> http://lists.osafoundation.org/pipermail/ietf-calsify/2005-October/000824.html 
> 
> 
> 
> The 2nd issue was brought up on the list in November 2006 by myself
> and it is is being tracked as issue 59 in the tracker.
> 
> http://lists.osafoundation.org/pipermail/ietf-calsify/2006-November/001341.html 
> 
> http://www.ofcourseimright.com/cgi-bin/roundup/calsify/issue59
> 
> Cheers,
> Bernard
> 
> Eliot Lear wrote:
>> While the issues list for 2445bis is officially closed, since I don't 
>> see a normative change in the text coming out of this discussion, I 
>> wouldn't object if someone proposed some example text to make the 
>> matter clear.  Please copy Bernard and this group directly on any such 
>> text.
>>
>> Eliot
>> _______________________________________________
>> Ietf-calsify mailing list
>> [email-masked]
>> http://lists.osafoundation.org/mailman/listinfo/ietf-calsify
> _______________________________________________
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> [email-masked]
> http://lists.osafoundation.org/mailman/listinfo/ietf-calsify
>

---

From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Mon Feb 19 08:41:44 2007

I would like to extend the scope of issue 10 to also cover the handling
of the DUE property when specified as a DATE value in a VTODO component.

The same way that the end time of a VEVENT can be explicitly specified
with the DTEND property or determined with the value of the DURATION
property combined with the value of the DTSTART property, the time at
which a VTODO is expected to be completed can be explicitly specified
with the DUE property or determined with the value of the DURATION
property combined with the value of the DTSTART property.

The same way that the DTEND property specifies the non-inclusive end
of events, the DUE property should be handled the same way for to-dos.

The following are examples of to-dos scheduled to start at 00:00:00 on
February 14, 2007 and expected to be completed before 00:00:00 February
15, 2007. These to-dos have until 23:59:59 on February 14, 2007 to be
completed before they become overdued.

    DTSTART;VALUE=DATE:20070214
    DURATION:P1D

    DTSTART:20070214T000000
    DURATION:P1D

    DTSTART;VALUE=DATE:20070214
    DUE;VALUE=DATE:20070215

    DTSTART:20070214T000000
    DUE:20070215T000000

The following are examples of to-dos scheduled to start at 00:00:00 on
February 14, 2007 and expected to be completed at the exact same time.

    DTSTART;VALUE=DATE:20070214
    DURATION:PT0S

    DTSTART:20070214T000000
    DURATION:PT0S

    DTSTART:20070214T000000
    DUE:20070214T000000

    DTSTART;VALUE=DATE:20070214
    DUE;VALUE=DATE:20070214

The implication here is that any application that presents a DUE property
of DATE value type as a "Due date" needs to substract one day to its value
since for an end user if some to-do is due on Feburary 14, 2007 he has
until the end of the day to complete the to-do (i.e., until 23:59:59 on
February 14, 2007). I've been told that some applications are presenting
this value as "Due by" to avoid this ambiguity.

Cheers,
Bernard

Bernard Desruisseaux wrote:
>>> matter clear.  Please copy Bernard and this group directly on any 
>>> such text.
>>>
>>> Eliot

---

From: mgk at webfeet.co.uk (Martin Kiff)
Date: Mon Feb 19 13:31:50 2007

Bernard Desruisseaux wrote:

> ... 
>    ...

My assumption is that DATE-TIME gives an instant; a time of zero extent. 
If you say DTSTART:20070214T000000 then that's the instant at the start 
of that second. (I think we are not really talking about a time with an 
extent of a second). That also seems to be understood when you talk 
about time, you say '3 o'clock'. That is 'an instant'...

However when you talk about dates, you talk about something which 
extends 24 hours (exception cases, mumble, mumble) _and_ you are also 
choosing a measure with lower precision. The way people talk about dates 
and times differs, at least in English, with the 'naive' view that a 
date extends to the end of the period... (and hence the need for 'due by')

Why should DUE;VALUE=DATE:20070215 particularly mean by the end of the 
previous working day? midnight? the start of that given working day? You 
would use 'VALUE=DATE' because you want that lower precision, if you 
want to be precise you give a DATE-TIME. We are imposing an unwarranted 
precision....

Regards, Martin

---

From: cyrus at daboo.name (Cyrus Daboo)
Date: Mon Feb 19 13:34:56 2007

Hi Bernard,

> of events, the DUE property should be handled the same way for to-dos.

+1

>From an analysis of a few clients it does look like the "due date" they 
display to users is the same value as gets used in the DUE property. The 
difference between "due on" and "due by" needs to be clear to users - but 
that distinction can be hard to represent. There is certainly a lot more 
variability in the way tasks/to-dos are presented to users that it would be 
hard come up with one true way to do that - but we should at least make 
explicitly clear what DUE represents in iCalendar data.

-- 
Cyrus Daboo

---

From: Bruce_Kahn at notesdev.ibm.com (Bruce Kahn)
Date: Fri Feb 23 09:22:13 2007

+1

> this value as "Due by" to avoid this ambiguity.

  There are be different ways to express the same intent.  If something 
has a due date of today then it I have until the end of the day to get it 
done.  The same situation can also be described by saying that whatever it 
is must be done by midnight tomorrow.  Users do not care how you write it 
as long as you can clearly and consistently express the correct intent. We 
need to clearly define the meaning in iCalendar so that UI's are free to 
express it accurately but in their own way to the user.

  I find that a "due by" meaning is much less ambiguous then a "due date" 
one but perhaps that's just me.

Bruce
=========
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