Subject: RE: Recurring Anniversary Instances?

From: [email-masked]
Date: Fri, 30 Jul 1999 12:01:24 -0400

Frank wrote:
>No, this is an error UNLESS the semantics are that when this occurs, it 
is a short-hand for >"take the time portion of the date/time" from the 
original DTSTART and DTEND. This makes >sense to me. For example, define a 
-T080000Z to -T090000Z meeting (a soiree for us >US-Eastern time zone 
folks ;-) ) event that is augmented with a RDATE property that >specifies 
5 other dates. The interpretation is that these 5 other occurrences are at 
the >same start/end as the first occurrence. 
>
>Other wise, there appears to be a value type mismatching here also 
introduces this hybrid >event that is both a traditional appointment and a 
day-long event. Too weird.

Before hopping into this exchange I would like to get some group 
clarification/acceptance of something:

Is DTSTART;VALUE=DATE:19990730 equivalent to 
DTSTART;VALUE=DATE-TIME:19990730T000000Z?

Is DTEND;VALUE=DATE:19990730 equivalent to 
DTEND;VALUE=DATE-TIME:19990730T235959Z (or should that be 
DTEND;VALUE=DATE-TIME:19990801T000000Z since its "non-inclusive")?

RFC 2445 has only the following relevant text (for DTSTART):

   The "VEVENT" is also the calendar component used to specify an
   anniversary or daily reminder within a calendar. These events have a
   DATE value type for the "DTSTART" property instead of the default
   data type of DATE-TIME. If such a "VEVENT" has a "DTEND" property, it
   MUST be specified as a DATE value also. The anniversary type of
   "VEVENT" can span more than one date (i.e, "DTEND" property value is
   set to a calendar date after the "DTSTART" property value).

   The "DTSTART" property for a "VEVENT" specifies the inclusive start
   of the event. For recurring events, it also specifies the very first
   instance in the recurrence set. The "DTEND" property for a "VEVENT"
   calendar component specifies the non-inclusive end of the event. For
   cases where a "VEVENT" calendar component specifies a "DTSTART"
   property with a DATE data type but no "DTEND" property, the events
   non-inclusive end is the end of the calendar date specified by the
   "DTSTART" property. [Snip]

4.8.2.4 Date/Time Start

   [Snip]

   Value Type: The default value type is DATE-TIME. The time value MUST
   be one of the forms defined for the DATE-TIME value type. The value
   type can be set to a DATE value type.

   [Snip]

   Description: Within the "VEVENT" calendar component, this property
   defines the start date and time for the event. The property is
   REQUIRED in "VEVENT" calendar components. Events can have a start
   date/time but no end date/time. In that case, the event does not take
   up any time.

There is no explicit declaration of what the start (or end) time default 
to in the VALUE=DATE cases.   Before continuing Id like to get concensus 
(or murmers)...

BTW: One potential example of Dans case is an IETF meeting.  It could be 
"a repeating all day" entry on my calendar for Monday thru Thursday and 
only "half a day" on Friday (using an RDATE;VALUE=PERIOD:...).  (Yes, your 
pending counter example of "a repeating 9AM-6PM" entry for Monday thru 
Thursday and 9AM-12PM Friday is another way to describe the same thing; 
its all in how the CU wants to treat it!)

Bruce
===========================================================================
Bruce Kahn                                INet: [email-masked]
Iris Associates                          Phone: 978.392.5335
Westford, MA, USA 01886                    FAX: and nothing but the FAX...
Standard disclaimers apply, even where prohibited by law...

---

From: "Dan Hickman" <[email-masked]>
Date: Fri, 30 Jul 1999 12:37:34 -0500

Bruce,

Technically, a DATE type value cannot be considered equal to a DATE-TIME
value because the types are different.  A DATE-TIME value specifies a
specific point in time, whereas a DATE value actually can be thought of as
specifying a range of time (19990730000000Z to 19990730235959).  Hence,
"All-Day".  This is useful concept when calculating Free Busy time because
you would show the whole day as being busy.

I agree that the RFC does not seem very clear for the DTEND of an event.  A
clarificaiton on the meaning of the term "non-inclusive" would be good.
Editors?  I would think that if an event had DTSTART:199900801 and
DTEND:19990802 then that would equal 2 full days of busy time (from
19990801000000Z to 19990802235959.  Correct?

Dan

    4.8.2.4 Date/Time Start

      [Snip]

      [Snip]

    There is no explicit declaration of what the start (or end) time default
to in the VALUE=DATE cases.   Before continuing Id like to get concensus (or
murmers)...

    BTW: One potential example of Dans case is an IETF meeting.  It could be
"a repeating all day" entry on my calendar for Monday thru Thursday and only
"half a day" on Friday (using an RDATE;VALUE=PERIOD:...).  (Yes, your
pending counter example of "a repeating 9AM-6PM" entry for Monday thru
Thursday and 9AM-12PM Friday is another way to describe the same thing; its
all in how the CU wants to treat it!)

    Bruce

    Westford, MA, USA 01886                    FAX: and nothing but the
FAX...

---

From: "Dan Hickman" <[email-masked]>
Date: Fri, 30 Jul 1999 13:22:49 -0500

Frank,

I don't think your short-hand suggestion would be the right way to interpret
it.  Either it is an error case or you can indeed have DATE occurrences in a
DATE-TIME event (and vice-versa).

We do need a concensus on this.  I have already added the capability to my
app and I know others have it as well (MS Outlook 97 does).  If it is an
error state, I will remove it, but we need to decide.

I agree that this would be a wierd type of event, but the spec doesn't
specifically disallow it and I don't think we should eliminate the option to
provide that functionality.

-Dan
is a short-hand for >"take the time portion of the date/time" from the
original DTSTART and DTEND. This makes >sense to me. For example, define
a -T080000Z to -T090000Z meeting (a soiree for us >US-Eastern time zone
folks ;-) ) event that is augmented with a RDATE property that >specifies 5
other dates. The interpretation is that these 5 other occurrences are at the
>same start/end as the first occurrence.
    >