[Ietf-calsify] rrule in timezone components
gsexton at mhsoftware.com
Tue Mar 6 11:34:50 PST 2007
Nigel Swinson wrote:
> MUST represent a unique time zone definition. This is necessary
> for some classes of events, such as airline flights, that start in
> one time zone and end in another.
Speaking from a position of semi-safety, and knowing that I can't be
burned at the stake for heresy in this may I ask a series of simple
I know these questions are as silly as questioning the fact that the sun
revolves around the earth, but please, bear with me.
1) In order to write a really accurate VTIMEZONE record you need a
source of information. The only really generic, solid source of this
information that I'm aware of is the Olson Time Zone Database.
2) The VTIMEZONE is in essence a series of rules, describing the
shifts of the time zone. IOW, it's perhaps a slightly more structured
rendition of the data in the Olson time zone database.
3) Some programming languages (Like Java in particular), and most
operating systems now use the Olson Time Zone DB as their reference
source. Java can convert time from one TZ to another TZ, with no effort.
4) VTIMEZONE is a unique thing, tied specifically to iCal, and not
used by any other standard.
Given all of these things, why would it not make sense to:
a) Deprecate VTIMEZONE and say that all VEVENT time zone references
must reference an Olson TZ Definition. After all, to write a really
decent VTIMEZONE entry you need to have this present anyway and be able
to parse it.
b) Create a standardized C/ (or other programming language) that can
read the Olson TZ database, and perform the conversion.
The benefits of this would be that developers could use a standard set
of library functions for time zone conversions rather than creating a
custom implementation. This library could be shared with other
applications and would achieve maturity and correctness very quickly.
So, my heretical question is why are you hanging on to VTIMEZONE
records? They're archaic and honestly there are just better things out
MH Software, Inc.
Voice: +1 303 438 9585
More information about the Ietf-calsify