Re: [calsify] JSCalendar: alternative to current all-day events

[Cyrus Daboo <[e-mail]>]

Hi Robert,

--On June 19, 2019 at 10:40:43 AM +0200 Robert Stepanek 
<[e-mail]> wrote:

>> That is because UTC (Z) is a time zone. It has nothing to do with all
>> day or anniversary. A 'Z' in addition to a TZID would be placing two
>> time zones into the same property. That would be nonsensical.
>
> We read
>  'The "TZID" property parameter MUST NOT be applied to DATE properties'
> as
>  'The TZID property parameter MUST NOT be applied to properties *with
> value type* DATE'.

Yes, but let me quote the whole sentence here because there is a slight 
problem with it:

          The "TZID" property parameter MUST NOT be applied to DATE
          properties and DATE-TIME or TIME properties whose time values are
          specified in UTC.

I think there is a comma missing here! There ought to be a comma after 
"DATE properties", which would make it clear that the whose clause applies 
to DATE-TIME and TIME only. i.e., the correct interpretation of this using 
parenthesis to group terms properly is:

    TZID MUST NOT be applied to either (DATE value properties) or 
((DATE-TIME or TIME) properties whose time values are
          specified in UTC)

I think the missing comma is a minor infraction, but one that could be 
fixed via an erratum if needed. In any case I think your further 
clarification of adding "with value type" is correct and could also be part 
of the erratum.

Even if one were not to agree with that, at best all that could be said is 
that 5545 does not define how TZID is interpreted when applied to a DATE 
value property. In all likelihood it would not be interoperable. I would 
guess that many iCalendar libraries might simply ignore it and not round 
trip it since they will likely use platform specific classes for date and 
date-time representation


-- 
Cyrus Daboo