Re: [calsify] SKIP was Re: AD review of draft-ietf-calext-rscale-03

Quite a discussion here, let me try to catch up.

As for FREQ=YEARLY;RSCALE=HEBREW;MONTHLY=5L;BYDAY=MO,TU,WE,TH,FR,SA,SU;SKIP=FORWARD
case, its clearly artificial and doesn't represent any real-world usecase,
so there's no preference for our users on how to handle it.

As was cleared above, SKIP behavior is clear for all Calendars except
Hebrew, and for all except Hebrew people will use SKIP=BACKWARD for most
usecases.

It is important to clear the Hebrew case, but lets keep in mind this we are
talking about a very narrow usecase for a relatively small number of users.
It will be unfair to complicate life for billions of Chinese or Hindu users
to make Hebrew case perfectly right.

Do I understand correctly that current draft allows to specify an RRULE for
all Hebrew cases, even though it looks ugly for Adar I 30th?

Grisha

On Tue Feb 03 2015 at 10:50:15 PM Marten Gajda <marten@dmfs.org> wrote:

>
> Am 03.02.2015 um 22:04 schrieb Cyrus Daboo:
>
> I think Ken's idea is that you apply the SKIP after BYMONTH only if the
> invalid data corresponds to an invalid leap month as opposed to a leap day.
> In which case the SKIP would not have applied after BYMONTH in your
> example. But I think a behavior like that is going to be really tricky for
> implementors to get right and hard to describe really well without having
> to delve into the gory details of RRULE processing.
>
>  Ah, got it.
>
> So, considering the following
>
> Applying SKIP=FORWARD after BYDAY on the following rule
>
>
> FREQ=YEARLY;RSCALE=HEBREW;MONTHLY=5L;BYDAY=MO,TU,WE,TH,FR,SA,SU;SKIP=FORWARD
>
> results in 30 instances in leap years and in non-leap years, since it
> would expand the week days in Adar I and roll them forward afterwards
>
> Applying SKIP=FORWARD after BYMONTH but before BYDAY results in 30
> instances in leap years, but 29 instances in non-leap years, since the
> weekdays would be expanded for Adar instead of Adar I.
>
> It's similar when the month following the leap month has more days than
> the leap month itself.
>
> In essence, applying SKIP after all BYxxx parts won't change the number of
> instances (given they don't fall on another instance), but Ken's approach
> might do that.
>
> Not sure what's preferable in this case.
>
>
>
>
> --
>
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