W3C home > Mailing lists > Public > public-vocabs@w3.org > May 2012

Re: webschema-ISSUE-16 (Add an Uncertain Date/Time mechanism): ISO8601 doesn't support imprecise dates, useful for cultural heritage, historical data, geneaology [Feedback on Schema.org]

From: Dan Brickley <danbri@danbri.org>
Date: Thu, 17 May 2012 11:01:20 +0200
Message-ID: <CAFfrAFrGiPUriqrxyvr8LrxFW0juz8pO_3f8nrw+KMwCEeMYpg@mail.gmail.com>
To: Web Schemas TF <public-vocabs@w3.org>, Jason Ronallo <jronallo@gmail.com>, rgardner@google.com, "Martin Hepp (UniBW)" <martin.hepp@ebusiness-unibw.org>
I've opened a new issue, detailed below. Two important sectors
(cultural heritage + historical/geneaological data) have need for
representing imprecise dates. The historical-data.org team are
suggesting usage of a Library of Congress spec,
http://www.loc.gov/standards/datetime/

Related discussion / research elsewhere:
http://wiki.whatwg.org/wiki/Time_element
http://pigsonthewing.org.uk/dates-and-coordinates-in-html5/
http://microformats.org/wiki/hcalendar-faq
http://html5doctor.com/time-and-data-element/

Related schema.org issues and proposals:

* http://www.w3.org/2011/webschema/track/issues/15 "ISSUE-15: Add Time
for xsd:time, DateTime for xsd:datetime"
* http://www.w3.org/wiki/WebSchemas/EventSchemaUpdate ... proposed
improvements to event schema

I've copied Robert Gardner and Jason Ronallo here, who independently
requested this. Jason - are you familiar with the L.O.C. design? Would
it adequately address the use cases you raise? Also Martin Hepp - re
your suggested addition of Time and DateTime, any thoughts on a class
structure that would allow imprecise dates? Also whether they might be
directly useful within Good Relations ecommerce scenarios.

For those of us who don't live-and-breath ISO-8601, it would also be
great to have a crisper description of where exactly ISO8601 fails
here. Presumably imprecise *times* are handled by omission; and
certain kinds of date vagueness too. The LOC spec goes further:

http://www.loc.gov/standards/datetime/pre-submission.html has a lot of
useful examples, though.  A brief extract here to give a feel for
things... "The characters '?' and '~' are used to mean "uncertain" and
"approximate" respectively, and in combination, i.e. '?~' to mean
uncertain and approximate."

* 1984? uncertain: possibly the year 1984, but not definitely
* 1984~ "approximately" the year 1984
* 1984?~ the year is approximately 1984 and even that is uncertain
* 199u some unspecified year in the 1990s.
* 1999-01-uu some day in January 1999
* 1984?/2004?~ interval whose beginning is uncertain but thought to be
1984, and whose end is uncertain and approximate but thought to be
2004
* 15uu-12-uu Some day in December in some year during the 1500s
* [..1760-12-03]  December 3, 1760; or some earlier date

This expressivity probably goes beyond schema.org's direct needs, but
there is value in being able to cite a common (even if only
'proposed') standard of some kind. I gather from
http://sun8.loc.gov/listarch/datetime.html that there has been
interest in submitting the library of congress doc to W3C. I'll get in
touch to find out status/stability.

cheers,

Dan

On 17 May 2012 10:35, Web Schemas TF Issue Tracker
<sysbot+tracker@w3.org> wrote:
> webschema-ISSUE-16 (Add an Uncertain Date/Time mechanism): ISO8601 doesn't support imprecise dates, useful for cultural heritage, historical data, geneaology [Feedback on Schema.org]
>
> http://www.w3.org/2011/webschema/track/issues/16
>
> Raised by: Dan Brickley
> On product: Feedback on Schema.org
>
>
> Use cases.
>
> 1. Cultural heritage information (Museums, Libraries, Archives)
>
> " The current processing rules in the specification do not handle many valid ISO8601 dates. As dates and ambiguity about dates is important for describing cultural heritage materials, hopefully the HTML5 processing rules can be adjusted to handle more valid ISO8601 dates. It seems as if the WHATWG has accepted a proposal to support year only dates, which is a start." [...]
> "Another kind of property a cultural heritage organization might like to add to a landmark or building like the Memorial Tower are the events related to the building. In this case the cornerstone was laid in 1922 and the tower dedicated on November 11, 1949. Other buildings could have events in their history like the dates they were designed or dates of renovations, derived from the drawings and project records. Museums may be interested in various events in the history of a painting including provenance and restorations. History museums and historical societies may also want to refer to various historical events that relate to their exhibits.",
> Jason Ronallo in http://journal.code4lib.org/articles/6400HTML5 Microdata and Schema.org (Code4Lib Journal, Issue 16, 2012-02-03, ISSN 1940-5758).
>
> 2. Historical data (e.g. geneaology)
> "Schema.org, Microformats, and Microdata all rely on the ISO 8601 date format, which does not support approximate dates. Review the Library of Congress's Extended Date and Time Format, which extends ISO 8601 and allows uncertain and approximate dates." [...]
> http://historical-data.org/
>
>
> Design options
>
> The historical-data.org initiative (whose schema is a strong candidate for inclusion at schema.org once such integration issues are resolved, see also http://www.w3.org/wiki/WebSchemas/HistoricalDataSchema ) suggests use of the Library of Congress "Extended Data and Time Format".
>
> See http://www.loc.gov/standards/datetime/
>
> Review comments on the suitability of this approach for schema.org's handing of imprecise dates would be useful.
>
>
>
Received on Thursday, 17 May 2012 09:01:52 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 22 May 2012 06:49:04 GMT