Subject: Re: To repeat or not...

From: [email-masked]
Date: Mon, 19 Jun 2000 18:06:07 -0400

John claimed:
>Suppose the EXRULE specifies that the
>DTSTART is not included? (Dumb, but valid.)

<DIGRESSION>
  We've been over this point before so I wont hammer it too hard again. 
The recurrence set is:

  DTSTART + ( RDATE + RRULE - EXDATE - EXRULE )

NOT

  DTSTART + RDATE + RRULE - EXDATE - EXRULE

  We argued over this in great detail before we RFC'd and there was no 
useful reason that the latter case should be allowed; otherwise you could 
entirely filter out an instance (ie: DTSTART and EXDATE w/the same 
values).  What do you have then??  A non-entity??

  I know that RFC 2445 has:

   The "EXDATE" property can be used to exclude the value specified in
   "DTSTART".

but it appears that our discussion we had waaay back in ~Nov '97 was not 
concluded according to any concensus we reached.  Check the thread titled 
"ical-04 Comments: Component Properties".  The two parts of 2445 under 4.8.5.1 Exception Date/Times and 4.8.5.2 Exception Rule also has contradictory text just above the above quote that says:

                       The "DTSTART" defines the first instance
   in the recurrence set.
...
                      The final recurrence set is generated by gathering
   all of the start date-times generated by any of the specified "RRULE"
   and "RDATE" properties, and excluding any start date and times which
   fall within the union of start date and times generated by any
   specified "EXRULE" and "EXDATE" properties.

  These contradictions need to be cleaned up in any errata we publish 
later on.  Frank???  Derik (maybe lurking??)?
</DIGRESSION>

  Im not going to willingly code any engine that allows me to 'nullify' an 
entity out by filtering it out using EXDATE/EXRULE.  There is no sound 
reason to allow it.  Ill involke the "Time to protect my users from 
nonsense." clause of my code before I buy into that.

  So, back to my original suggestions.  The RFCs already coded up the 
RESPONSE-STATUS:2.8 case for doing collapsing of repeating entries into a 
singular one.  John, are you suggesting we just ignore that option and 
reject the entire request using RESPONSE-STATUS:3.13 (or was that 3.6?)?? 

What do others think: Flatten to singular instance or reject it all out of 
hand?

Bruce
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Bruce Kahn                                INet: [email-masked]
Iris Associates                          Phone: 978.392.5335
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