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Re: HTML+RDFa (3.1 Document Conformance)

From: Mark Birbeck <mark.birbeck@webbackplane.com>
Date: Wed, 16 Sep 2009 23:27:47 +0100
Message-ID: <640dd5060909161527k1d1034f5n10209c409ff5d8b0@mail.gmail.com>
To: Manu Sporny <msporny@digitalbazaar.com>
Cc: public-rdf-in-xhtml-tf@w3.org
Hi Manu,

> Basically, if the string "RDFa 1.0" exists in the @version attribute
> (either surrounded by '+' characters or not), then the document contains
> RDFa 1.0 syntax. This allows people to do stuff like:
> version="SVGTiny 1.2+RDFa 1.0" or
> version="HTML+RDFa 1.0+CoolLanguageExtension 2.1"
> This is beneficial because we do want RDFa to be easily mixed-in with
> future element/attribute-based languages.

Ah...a chance to resurrect an old proposal of mine. :)

The W3C already has a way to write these kinds of sequences, which is
the 'feature string' notion used in the DOM [1]. We could use the same
thing, but surface it to the markup, rather than confining it to the
DOM API. This is something I've been keen to see happen for a long
time, with my XForms hat on.

If you're not familiar with them, the DOM feature strings provides a
way to list features, with optional version numbers. They are used
either as part of a request for an object ('give me an interface that
supports DOM Events'), or as part of a report on what objects are
supported ('do you support version 2 of DOM Events').

The DOM Level 3 Core gives an example that effectively maps to this [2]:

  obj.getDOMImplementationList("XML 3.0 Traversal +Events 2.0");

The module name is the one used in each DOM API spec -- 'Event',
'XML', 'Events', 'XForms', 'SVG', etc. -- and if you don't specify a
version number, it means that you don't care what version is used.
(The '+' means that the interface must be directly accessible, which
doesn't concern us.)

So the exact same notation could be used in markup to indicate what
functionality a platform must support, in order to process the current
document. For example:

  @version="HTML RDFa"

means 'this document will work on a DOM that supports any version of
HTML, and any version of RDFa'.

  @version="HTML RDFa 1.1"

means 'this document will work on a DOM that supports any version of
HTML, but it must support _at least_ version 1.1 of RDFa'.

And so on.



[1] <http://www.w3.org/TR/DOM-Level-3-Core/core.html#DOMFeatures>
[2] <http://www.w3.org/TR/DOM-Level-3-Core/core.html#ID-getDOMImpl>

Mark Birbeck, webBackplane



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Received on Wednesday, 16 September 2009 22:28:30 UTC

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