Subject: Re: Omit VTIMEZONE when using global identifiers?

From: [email-masked]
Date: Thu, 19 Apr 2001 10:35:59 -0400

Alan noted:
>    The presence of the SOLIDUS character (US-ASCII decimal 47) as a
>    prefix, indicates that this TZID represents a unique ID in a globally
>    defined time zone registry (when such registry is defined).
>
>         Note: This document does not define a naming convention for time
>         zone identifiers. Implementers may want to use the naming
>         conventions defined in existing time zone specifications such as
>         the public-domain Olson database [TZ]. The specification of
>         globally unique time zone identifiers is not addressed by this
>         document and is left for future study.

Ok, this may be hair splitting but the _only_ place that "globally unique" and TZIDs are mentioned is in the Note part 
of the text.  Its not actually called for in the normalative text.  The 
phrase in the Note is talking about any TZID that is created with a '/' 
prefix and making them globally unique.  This is good (once it begins) 
even if it does not directly address the issue of changes to a unique 
entry.  That is out of scope for iCalendar right now.

If you reread the ABNF for TZID you will see it is simply defined as:

     tzidparam  = "TZID" "=" [tzidprefix] paramtext CRLF

     tzidprefix = "/"

The paramtext is NOT defined as globally unqiue so it is perfectly 
reasonable to have my iCal engine and Johns generating the same 
TZID=We_rule_TZID values in separate iCalendar streams...  The globally 
uniquenes only applys to any future IANA (or other body) registered 
values, not to ones that anyone else generates.  Now I may have come full 
circle on this argument but Im just now swapping back in so appologies now 
just in case...

Bruce
===========================================================================
Bruce Kahn                                INet: [email-masked]
Iris Associates                          Phone: 978.392.5335
Westford, MA, USA 01886                    FAX: and nothing but the FAX...
Standard disclaimers apply, even where prohibited by law...

---

From: Alan Davies <[email-masked]>
Date: Mon, 23 Apr 2001 09:57:33 -0400

To resplit some more hairs- if you reread the first passage,
(which was quoted from the RFC) you'll see that the words "unique"
and "globally" do appear in the normalative text, in the phrase

     "represents a unique ID in a globally defined time zone registry"

All taking part in the discussion realised that the paramtext for TZIDs
does not _have_ to be globally unique, we were discussing cases where
the '/' prefix is used to imply a globally unique ID.

--Alan

At 10:35 2001-04-19 -0400, [email-masked] wrote:

>Ok, this may be hair splitting but the _only_ place that "globally unique" 
>and TZIDs are mentioned is in the Note part of the text.  Its not actually 
>called for in the normalative text.  The phrase in the Note is talking 
>about any TZID that is created with a '/' prefix and making them globally 
>unique.  This is good (once it begins) even if it does not directly 
>address the issue of changes to a unique entry.  That is out of scope for 
>iCalendar right now.
>