[caldeveloper-l] DTSTART that doesn't match RRULE pattern

[Helge Hess]

On 11. Oct 2018, at 02:54, Neil Jenkins <neilj at fastmailteam.com> wrote:
> On Thu, 11 Oct 2018, at 6:46 AM, Cyrus Daboo wrote:
>> The intent of that was to effectively deprecate the behavior of DTSTART not 
>> matching the pattern (without making it outright illegal by using a MUST), 
>> with the idea that a future update to 5545 would switch to MUST.
> 
> That's lovely in theory, but in practice there are still many clients that allow you to create such events. Apple Calendar, to take one example.

I really don’t think the idea of a standard is to document bugs in software. That DTSTART is an extra RDATE was never ever the intention.

To deal with b0rked software, you already have the User-Agent/PRODID and you can switch modes based on that. (IIRR that is already necessary necessary to deal with older iCal.app versions.)

As Cyrus says, 5545 clearly states what you as a vendor SHOULD do. And that doesn’t say “match the Apple Calendar behaviour” ;-)

hh