LISTSERV mailing list manager LISTSERV 16.0

Help for DATETIME Archives


DATETIME Archives

DATETIME Archives


DATETIME@C4VLPLISTSERV01.LOC.GOV


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Monospaced Font

LISTSERV Archives

LISTSERV Archives

DATETIME Home

DATETIME Home

DATETIME  February 2013

DATETIME February 2013

Subject:

Re: Precision better than one second

From:

"Byrd, Donald A." <[log in to unmask]>

Reply-To:

Discussion of the Developing Date/Time Standards <[log in to unmask]>

Date:

Sun, 17 Feb 2013 09:13:55 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (128 lines)

Edward's message hints at the endless complexity of time descriptions
in the real world! I'm very interested myself in everything Edward
wants. But to avoid getting bogged down in details ourselves _and_ to
save people who want to implement EDTF and don't need fancy features,
let's not forget EDTF's division into levels, which I think is a very
good idea.

* For EDTF Level 0, I propose we add _only_ the ISO 8601 syntax for
fractional seconds used by xsd:dateTime, exactly as suggested by
Saasha. As for whether the number of decimal digits after the dot in
EDTF-born data should be potentially unlimited, I'm pretty sure that
both 8601 and XSD allow that, but 8601 suggests implementations specify
a maximum number of digits they handle; I propose EDTF do the same
thing, specifically allowing that number to be zero.

So an implementation might allow any of these descriptions of a certain time:

2013-02-16T02:03:01.7
2013-02-16T02:03:01.667
2013-02-16T02:03:01.6666667
2013-02-16T02:03:01.66666666666666666666666666666667

...assuming it specified enough digits. NO other way to describe that
time with better than 1 sec. precision would be allowed. If the
implementation supports zero digits after the dot, none of those
descriptions would be legal.

* For EDTF Level 1 or 2, I propose we add fractional minutes and
fractional hours, interpreting them exactly as suggested by Saasha.

* For EDTF Level 2, I propose we _consider_ support for the kind of
thing Edward mentions -- essentially, specifying completely arbitrary
non-decimal precision (is that a fair statement, Edward?). But I
suspect it'd make more sense to add it the list of future features in
Annex A, with a high probability of it ending up in Level 3.

--Don


On Sat, 16 Feb 2013 20:56:16 +0100, "Edward C. Zimmermann"
<[log in to unmask]> wrote:

> On Fri, 15 Feb 2013 16:52:48 +0100, [UTF-8?]SaaÅ¡ha Metsärantala wrote
>> Hello!
>>
>> > "For time, is hour:minute:second sufficient, or do we need to support
> fraction of a second?"
>> In the library / museum / archive world, expressing something similar to
>> "during the 1870'ies approximately" is often a more useful feature than a
>
> The two are hardly exclusive. I think I've been quite strong in voicing my
> position on precision/readability and data reliability/repeatability.
> Decade, century or .. "precision" is no different than minute, second,
> millisecond, nanosecond,... "precision".
>
>> precision at the millisecond's level. This is one of the reasons why there
>
> Millisecond is a decimal model of precision. There are others.
>
> The Jewish time model is an example of a non-decimal time model that is
> currently widely used.
>
> Jews all over the world use a time with a precision of 1/72 a time degree
> (Halokim) or 3 1/3 seconds (1/18 minute). The precision of the date/time for
> events such as new month (defined by moon) is 3 1/3 seconds.
>
> Just as we have ..., decade, year, month, day, hour, minute, second,
> millisecond,... models in the ISO world we have also ...,day, hour, minute,
> halokim, regaim (76 regaim = 1 halokim) in the Jewish ... (to make
> things even
> more complicated the time for lunar festivals is the time of the event in
> Jerusalem)
>
> Since hour, minute, second are based on degrees and are not decimal (60
> seconds= 1 minute, 60 min= 1 hour, 24 hours = 1 day) to demand that
> the minute
> be divided by tens is a break in design---- the Napoleonic system went the
> other way to define 1 year = 10 months, 1 day = 10 hours, 1 hours = 10 ...)
>
>> was a need for EDTF and the reason why we focused on approximations (and
>> other features) more than fractions of seconds.
>>
>> If you consider it is useful (and it may probably be useful in some
>> cases), it is OK for me to add this feature in EDTF. It is quite easy to
>> modify the BNF for that and there should probably not be major problems to
>> implement a parsing taking fractions of seconds into account. There are
>> several more crucial (but also more difficult to describe and implement)
>> features to be added to EDTF and I consider that fractional seconds is not
>> a priority, but I consider it is OK to add this feature at level zero,
>> remembering that it is part of xsd:dateTime
>> http://www.w3.org/TR/xmlschema11-2/#con-dateTime-day to which I suggest to
>> stick. Let's keep in mind though, that according to
>> dotat.at/tmp/ISO_8601-2004_E.pdf (page 16) ISO_8601 reads:
>>
>> > "the decimal fraction shall be [...] the comma (,) or full stop (.). Of
> these, the comma is the preferred sign."
>>
>> and
>>
>> > "a decimal fraction of hour, minute or second may be included."
>>
>> whereas xsd:dateTime only allows dots (full stops) as separators and only
>> allows fractional seconds (not fractional hours nor fractional minutes).
>>
>> This should not be a problem though, because EDTF level zero is defined as
>> a profile of ISO_8601.
>>
>> Regards!
>>
>> [UTF-8?]Saašha,
>
>
> --
>
> Edward C. Zimmermann, NONMONOTONIC LAB/BSn
> http://www.ibu.de/IB_Engine
> Umsatz-St-ID: DE130492967
>



--
Donald Byrd
Woodrow Wilson Indiana Teaching Fellow
Adjunct Associate Professor of Informatics
Visiting Scientist, Research Technologies
Indiana University Bloomington

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

August 2019
February 2019
December 2018
November 2018
October 2018
January 2018
August 2017
July 2017
June 2017
April 2017
March 2017
February 2017
August 2016
July 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
December 2014
November 2014
March 2014
September 2013
May 2013
February 2013
October 2012
September 2012
August 2012
May 2012
March 2012
December 2011
November 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
February 2010
January 2010
December 2009
November 2009

ATOM RSS1 RSS2



LISTSERV.LOC.GOV

CataList Email List Search Powered by the LISTSERV Email List Manager