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Re: Circa. dates

From: Dan Brickley <danbri@google.com>
Date: Sat, 28 Feb 2015 10:42:41 -0800
Message-ID: <CAK-qy=7BGHj9_K_ujhQ48bs8RUYvMqNGQHtSxbdh6UV+xH76zw@mail.gmail.com>
To: "Wallis,Richard" <Richard.Wallis@oclc.org>
Cc: "public-vocabs@w3c.org" <public-vocabs@w3c.org>
On 28 February 2015 at 09:51, Wallis,Richard <Richard.Wallis@oclc.org> wrote:
> Hi all,
> With colleagues I have been looking at how we might handle historical
> approximate dates in Schema.org.  The initial requirement being to be able
> to describe an old book or manuscript published say in approximately 1765.
> A common need in the bibliographic world, with the normal string based
> solution being “circa. 1765”, or “c. 1765” - Wikipedia providing some
> examples.

This has come up before, see

I recently migrated our old issue tracking this over to Github, see
https://github.com/schemaorg/schemaorg/issues/242 and have just linked
this thread from it.

There is some work towards addressing these issues at
In particular a draft of a spec that never eventually went to W3C is
here: http://www.loc.gov/standards/datetime/pre-submission.html

Another approach would be to have constructions that treated certain
famous/named periods as entities and used sameAs to Wikipedia/Wikidata
or other authorities (SKOS vocabs etc too).


> The knee-jerk reaction was to suggest some sort of approximateDateCreated
> property for CreativeWork which would not only help us bibliographic folks
> but also those in museums and galleries with similar date approximation
> needs.
> Broadening the analysis it became clear that this need could be applicable
> in most any case where you would expect a Date in the range of a property.
> birthDate, deathDate, dateCreated, datePublished, foundingDate, all being
> all potential candidates for Circa style dates.  Rolling things into the
> future you could imagine other examples such as wanting to describe the last
> serviced date of a vehicle being circa 2013.
> So how to solve this in a simple, yet generic, way?
> We could take advantage of the default "if you haven’t got a specified type
> for a property, a Text is acceptable” pattern in Schema, and just put in a
> text string with a defined format: “c.1765”.
> Perhaps a more appropriate solution would be to define a new data type, to
> be added to the range of suitable properties.
> My pragmatic (KISS and don’t break stuff) view of this leads me to suggest a
> new data type named ‘circaData’, or maybe 'approximateDate' as a subType of
> Date.  With descriptive information in the Type definition explaining
> why/how you would use it in the use cases I describe above.
> This approach would add this important functionality, for those describing
> old stuff, without the need for major upheaval across the vocabulary, and
> would at least default to a date for those that do not care or look for such
> approximation aspect of dates.
> ~Richard
Received on Saturday, 28 February 2015 18:43:09 UTC

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