Re: [calsify] JSCalendar: fractional seconds

["Ken Murchison" <[e-mail]>]

As a related topic, a libical user/developer submitted a PR to add millisecond precision to time values. I haven’t committed it because it simply changes the DATETIME values which certainly isn’t backwards compatible. I suggested a new VALUE type but even that isn’t compatible with unaware clients. 

Regardless, there does appear to be *some* desire to have fractional seconds support in iCalendar. 

--
Kenneth Murchison
Cyrus Development Team
FastMail US LLC
[e-mail]



On Thu, Jun 6, 2019, at 8:04 AM, Marten Gajda wrote:
> Is this parameter is meant to preserve the fractional seconds for round-trips or are iCalendar clients encouraged to use the value?

> I mean, would a client that's aware of X-FRACSEC have to match RECURRENCE-IDs ,RDATES and EXDATES taking the fractional seconds into account? 

> I think we should advise against that and make clear that this is not meant to increase the precision of times in iCalendar, but merely to preserve it.

> Btw, how do we cope with unaware clients doing partial updates? I.e. a client which is not aware of X-FRACSEC adds a new recurrence-override (not adding X-FRACSEC to RECURRENCE-ID). When being converted back to JSCalendar, this would result in an additional instance instead of an override.

> Marten

> Am 06.06.19 um 13:49 schrieb Robert Stepanek:
>> It just occurred to me that the current JSCalendar RFC draft ambiguously defines if fractional seconds are allowed in the LocalDate time type.
>> 
>> To be clear: we intend to allow fractional seconds in the start property (and any other LocalDate property). The next version of the RFC draft will define this more clearly.
>> 
>> Unfortunately, fractional second date-times and durations can not be round-tripped out of the box with iCalendar. We will define an iCalendar extension parameter in the informational guide for mapping iCalendar and JSCalendar (draft-ietf-calext-jscalendar-icalendar):
>>  * X-FRACSEC of value type INTEGER
>>  * This parameter MAY be set on iCalendar properties of type DATE-TIME or DURATION. It MUST NOT be set more than once per property.
>>  * The value of this parameter defines the fractional seconds of the DATE-TIME or DURATION type.
>>  * This will allow iCalendar implementations not being aware of this extension parameter to display the time value "good enough" with second precision.
>> 
>> Please let me know if you prefer another approach.
>> 
>> Cheers,
>> Robert
>> 
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> -- 
Marten Gajda
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