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[whatwg] Annotating structured data that HTML has no semantics for

From: Jonas Sicking <jonas@sicking.cc>
Date: Tue, 9 Jun 2009 02:15:25 -0700
Message-ID: <63df84f0906090215n9e3d816m695b6026fb4a42b0@mail.gmail.com>
>> Some of the improvement suggestions that I have heard that sounds
>> interesting, though possibly for the next version of microdata.
>>
>> * Support for specifying a machine-readable value, such as for dates,
>> colors, numbers, etc.
>
> I expect we will add support for these based on demand, the same way we
> added <time> in the first place.

Using dedicated elements for each data type seems like it will
eventually bloat the language. For example what use would a <color>
element or a <number> element do? If instead mashine readable values
could be added using a generic method, such as a 'itemvalue' or
'propvalue' attribute, each microdata format can define how to
interpret the values, be they numbers, dates, body parts, or chemical
formulas.

>> I even wonder it would allow replacing the <time> element with a
>> standardized microformat, such as:
>>
>> Christmas is going down on <span item="w3c.time"
>> itemvalue="12-25-2009">The 25th day of December<span>!
>
> I don't really understand how that would be better than dedicated
> elements.

The idea would be to reduce the size of the language. I.e. if a
feature isn't heavily used, it might be better expressed as a
microdata format. For example, why didn't you add elements for bibtex
or vCard, but instead used microdata?

However, it's quite possible that <time> is going to be commonly used
enough that it's worth using an element rather than a microdata
format.

Another reason is as a test of the microdata feature itself. Microdata
is a sort of extension mechanism to HTML 5. In software development,
it is common to test your extension system by developing parts of the
product using the extension system. This way you can both keep the
core code small, and you get a good test bed for your extension
system.

You have already done this with the "predefined vocabularies", and
apparently the lack of ability to define a mashine readable value
separate from the human readable one was not a problem. However it
would seem that the same does not hold true for <time>.

>> * Support for tabular data.
>
> This would be nice if we can find a way to do it that doesn't put undue
> burdens on simple implementations. (e.g. I would imagine that while a
> microdata implementation today can be a few hundred lines total, adding
> support for the table model could easily double that.)

Quite possibly.

In both these cases I'm perfectly happy to wait with adding more
features to microdata for now and see if what we have is successful,
before we start over engineering it to cover every imaginable case.

/ Jonas
Received on Tuesday, 9 June 2009 02:15:25 UTC

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