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Re: Open intervals for temporalCoverage ?

From: Dan Brickley <danbri@google.com>
Date: Wed, 14 Sep 2016 11:49:04 +0100
Message-ID: <CAK-qy=4pWtdwwt4gwgLGSceaSz8Vo+-W6AXfnRMJxP=juJmw0g@mail.gmail.com>
To: Richard Wallis <richard.wallis@dataliberate.com>
Cc: Thomas Francart <thomas.francart@sparna.fr>, "schema.org Mailing List" <public-schemaorg@w3.org>
On 14 September 2016 at 11:14, Richard Wallis
<richard.wallis@dataliberate.com> wrote:
> As the documentation for temporalCoverage states, it expects ISO 8601 time
> interval format, so the question lies there.
>
> Your understanding I believe is correct, that the current version of the
> standard ( ISO 8601:2000 ) does not support open ended time intervals.
>
> In Dublin Core, which bases its formats on ISO 8601,  open ended intervals
> are supported but explicitly state “This representation of an open date
> range is not compatible with the representation of a time-interval defined
> by ISO8601:2000.”
>
> This has been the subject of a short
> https://github.com/project-open-data/project-open-data.github.io/issues/415.
> I support their conclusion that an open ended time period would be currently
> best represented by the appropriate use [or non-use] of schema:startDate and
> schema:endDate.

The DC specs were done a while ago - is there any chance ISO 8601 has
evolved since then? open-ended seems a reasonable requirement, so long
as it doesn't make the syntax ambiguous.

I looked around for others hitting this situation and found at least
http://www.lyberty.com/meta/iso_8601.htm ... there may be more out
there along similar lines:

"""

Open Date Ranges

Some record-keeping metadata requires specification of date ranges.
For example, a Business Activity may only have been valid between the
years 1949 and 1953. ISO 8601 allows the specification of date ranges
using a forward slash (/) to separate dates representing the start and
end of the range. For example, "1949/1953". Recordkeeping metadata
also requires specification of open date ranges. For example, an
Agency may have an operational period from July 1st 1998 until the
present date. Open date ranges such as this are not defined in ISO
8601. The RKMS Extension to ISO 8601 allows open date ranges to be
specified by extending the ISO 8601 syntax to allow the omission of
either the start or end date in the range. Acceptable RKMS date ranges
are then:

Closed date range: DateTime/DateTime (e.g. 1949/1953-01-01)
Date range with unknown start: /DateTime (e.g. /2000-12-31T11:59:59)
Date range with no end date: DateTime/ (e.g. 1998-07-01/)"""

Dan
Received on Wednesday, 14 September 2016 10:49:36 UTC

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