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[Bug 13465] New: Implement datatyping in Microdata

From: <bugzilla@jessica.w3.org>
Date: Sat, 30 Jul 2011 14:37:02 +0000
To: public-html@w3.org
Message-ID: <bug-13465-2495@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=13465

           Summary: Implement datatyping in Microdata
           Product: HTML WG
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: HTML Microdata (editor: Ian Hickson)
        AssignedTo: ian@hixie.ch
        ReportedBy: msporny@digitalbazaar.com
         QAContact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-wg-issue-tracking@w3.org,
                    public-html@w3.org


This feedback is filed as a personal comment and is not intended to be any sort
of official feedback from any standards working group.

Microdata currently has no way of expressing data types using the syntax. This
is an issue for at least two reasons:

1. It's impossible to determine whether or not a value is an IRI, or a text
string that looks like an IRI. This is an issue for forward-compatibility
reasons, as a string intended to be a colon separated value today, e.g.
dc:title, could be interpreted as a IRI tomorrow if a new scheme 'dc' were
created. There is no deterministic way to understand the authors intent without
datatyping in this case.

2. It is useful to applications to understand the datatype of a particular item
in a machine-readable way. Asking application developers to create a universal
way of figuring out what "45" means in a generic data processor is eased by
tagging the value with a datatype. In one example, 'delta' could be expressed
in "degrees Celcius, a unit of temperature measurement", in another "degrees, a
unit of angle measurement".

Ensure that the data-typing carries through in the JSON representation in some
way. JSON-LD demonstrates how this can happen via the @context without making
the data values used in the JSON more complex.

One suggestion is to create something in the Microdata spec that ensures that
Web vocabularies are machine-readable and then set a "default type" for
Microdata Web vocabularies. This would make it so that the complexity of
datatyping is handled in the Web Vocabulary and does not have to be expressed
by the Web author. Ideally, you would be able to specify a default type for Web
Vocabulary terms as well as override that default type using something like
@itemproptype.

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Received on Saturday, 30 July 2011 14:37:07 GMT

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