Subject: Re: [Tzdist] #10 We should truncate (entirely) truncation ;-)

From: Cyrus Daboo <[email-masked]>
Date: Sat, 22 Nov 2014 10:24:06 -0500

Hi Tim,

--On November 21, 2014 at 12:30:02 AM -0500 Tim Parenti 
<[email-masked]> wrote:

>> This does still leave the problem that some rule sets may have a
>> truncated range due to the rule rather than the selected truncation
>> range?
>>
>
> Exactly.  It simply doesn't make sense to me to have TZ-UNTIL for one
> response type, but no equivalent parameter for the other.
>
> I suppose the starting bound is implicit in both the request and the
> response (by virtue of how the first observance is returned).  Maybe just
> call it "tz-until" and include it in the same situations we would include
> it for a VTIMEZONE response?  (That is, whenever the end is truncated
> either by request or by rule.)

OK, so we need to be clear about the truncation process. Section 3.8 
describes a server-based truncation with advertisement of the associated 
truncation ranges. I think what you are describing is more akin to a 
"validity" range for the time zone - something that the IANA DB does not 
currently provide (beyond perhaps LMT the starting point, there is no "end 
point"). However, that may not be true for all publishers.

So I think we need to cover both cases. We have truncation already covered. 
We then need to handle the range of validity. For that TZUNTIL covers the 
end point and the first observance provides a start point. If the range of 
validity is contained within the truncation ranges then yes, we will need 
to advertise that in the expand response.

Given that, I will adopt your proposal to advertise the range of validity 
for the observances via additional members in the response. It probably 
makes sense to require those in every response even if the observances 
fully span the requested start/end range.

-
Cyrus Daboo

---

From: Tim Parenti <[email-masked]>
Date: Mon, 24 Nov 2014 16:22:51 -0500

On 22 November 2014 at 10:24, Cyrus Daboo <[email-masked]> wrote:

> I will adopt your proposal to advertise the range of validity for the
> observances via additional members in the response. It probably makes sense
> to require those in every response even if the observances fully span the
> requested start/end range.

Yes, this makes sense to me.

--
Tim Parenti