If a provision is added to specify the Julian calendar, it will be
necessary to distinguish the Julian calendar as observed in Rome since
45 BC versus the Julian calendar as extrapolated backward from the
middle ages. They did not agree until around AD 8.
On 2010-11-08 11:46 AM, Edward C. Zimmermann wrote:
> The names are, I think, the least problem--- we can just define a controlled
> The biggest problem is that calendars such as the Jewish/Hebrew don't have
> reversible transformations into Gregorian or Julian unless time and day of the
> week are also specified--- from which one could determine if its before
> sundown at the place (and, in fact, the same location may have two different
> representations for two different people as there are sometimes multiple
> customs that might be called upon to define sundown).
> Keeping to the Jewish/Hebrew calendar (and the Babylonian and other Lunisolar
> calendars as well) we also can't resolve completely against our min/sec model.
> The Jewish hour is divided into 1080 units: 72 units per degree celestial
> rotation or 360 * 72/ 24. Going back to Hebrew/Jewish now from a transformed
> date, however, won't work since the Julian/Gergorian day ends at Midnight and
> there is no way to determine the date. Its roughly based upon the stars
> viewable from the location--- with good visibility--
> and so these is insufficient information in a date/time to go back.
> On Mon, 8 Nov 2010 10:06:48 -0500, Denenberg, Ray wrote
>> From: Discussion of the Developing Date/Time Standards
> [mailto:[log in to unmask]] On Behalf Of Simon Grant
>> Sent: Saturday, November 06, 2010 8:13 AM
>> To: [log in to unmask]
>> Subject: Re: [DATETIME] Extended Date/Time Format DRAFT specification for
> review through December 6
>> "3. Miscellaneous / Calendar
>> It seems a no-brainer to define "julian" as an alternative to "gregorian",
> though other calendars would presumably be more difficult, as they may have
> different components. At least, in my limited understanding, Julian and
> Gregorian calendars have the same components."
>> I took my cue here from the draft VCard specification,
> http://tools.ietf.org/html/draft-ietf-vcarddav-vcardrev-11#section-5.7, and
> also the draft HTML5 spec (at least the WHATWG version if not WC) calendar
> parameter (calscale), in which they define only the single value, 'gregorian'.
>> My thinking is, I am hesitant to specify any values for calendars at all, as
> I am unaware of any established vocabulary for calendar names (however, if
> there is one, I would be interested in revisiting this issue). I am not
> terribly reluctant to specify 'gregorian' because the vCard specification uses
> that term, and even though that's a draft spec, if's a safe bet that it won't
> change. I'm sure if's a safe bet that when Julian calendars are accomodated
> the term 'julian' will be used. But there may also be good reasons why vCard
> and the HTML people didn't want to include it now, perhaps because if they did
> then the spec would need to detail the differences.
>> Anyway this is open for discussion.
> Edward C. Zimmermann, NONMONOTONIC LAB
> Basis Systeme netzwerk, Munich Ges. des buergerl. Rechts
> Office Leo (R&D):
> Leopoldstrasse 53-55, D-80802 Munich,
> Federal Republic of Germany
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