Re: [calsify] [Technical Errata Reported] RFC5545 (5505)

[Bernard Desruisseaux <[e-mail]>]

Hi Cyrus,

Should TZID allow quoted values?  One could easily answer: Why not!   In 2018, though I’m more tempted to ask: Why?

As you rightly mentioned, we now have the IANA Time Zone Database.

Why would someone want / need to specify   TZID=GMT-03:00  instead of  TZID=Etc/GMT-3?

Perhaps this iCalendar inconsistency is actually a good thing for interoperability!

Finally, for the record only, not that it matters, Mozilla.org did use the tzprefix at some point.  See:

	https://www.google.ca/search?q=TZID=/mozilla.org

Cheers,
Bernard

> Le 26 sept. 2018 à 10:27, Cyrus Daboo <[e-mail]> a écrit :
> 
> Hi Michael,
> 
> --On September 26, 2018 at 1:00:02 PM +0200 Michael Douglass <[e-mail]> wrote:
> 
>> My belief is that parsers are already expecting this. Certainly ical4j
>> and libical already accept quoted values.
>> 
>> In any case it's broken as it stands. Parameter escaping isn't an option
>> as it assumes parameter value quoting is an option.
> 
> I agree this should be fixed, but the proposed change in the erratum is wrong. This was the proposed new definition:
> 
>      tzidparam  = "TZID" "=" [tzidprefix] param-value
> 
> That does not work because it would allow the optional tzidprefix (which is a single "/" character) to appear before the first quote of any quoted string. I think you really need:
> 
> tzidparam  = "TZID" "=" ([tzidprefix] paramtext) /
>                       (DQUOTE [tzidprefix] *QSAFE-CHAR DQUOTE)
> 
> That ensures the tzidprefix appears inside the quoted string, if that construct is used.
> 
> That said, I don't think I have ever seen tzidprefix being used. It was meant to be used to indicate the the ID was from a globally defined registry - well we have that now (IANA tzdb) and we aren't using the prefix. I would suggest any future revision of 5545 should drop tzidprefix as a formal syntax element, and instead just mention that the tzid value may be prefixed.
> 
> FYI I checked my 5545 code and all implementations parse and generate paramaters based on the generic definition of a parameter:
> 
>    param         = param-name "=" param-value *("," param-value)
> 
> So a quoted TZID would be fine.
> 
> -- 
> Cyrus Daboo
> 
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