[whatwg] Creative Commons Rights Expression Language

Henri Sivonen hsivonen at iki.fi
Thu Aug 21 03:52:37 PDT 2008

On Aug 21, 2008, at 10:49, Dan Brickley wrote:

> I encourage you to (re)-read http://www.w3.org/Submission/2008/SUBM-ccREL-20080501/ 
>  ... the spec explains that all of CC's concrete markup requirements  
> are addressed by the HTML additions in the RDFa spec.

The RDFa spec doesn't make any additions to HTML. It only specifies  
additions to XHTML, and those additions use a Namespace-dependent anti- 
pattern, so they aren't portable to HTML.

> In other words, adding 'about', 'property', 'resource', 'datatype'  
> and 'typeof' and a namespace-URI association convention to HTML5  
> wouldn't merely be addressing the important needs of the Creative  
> Commons community.

It seems to me that the Creative Commons community has more pressing  
needs that aren't related to RDF syntax. Specifically: Making people  
to refer to license URI at all, making them to identify which CC  
license they mean, making them understand what permissions they are  
giving irrevocably to others upon granting a license and making them  
understand what licenses used by others mean (NonCommercial, anyone?).  
Syntax doesn't solve any of these.

People don't know what they are doing when they flip those Flickr  

At least in a non-RDF context, pointing to the license by URI seems  
too hard. See

Also note that even CC leadership omits the license URI. I encourage  
you to examine the last frames of the videos at http:// 
lessig.blip.tv/. The latest video (http://lessig.blip.tv/file/ 
1185352/) works as an example. Whenever the last frame acknowledges  
the use of CC-licensed photos, it doesn't show the URI of the license.  
In fact, it doesn't even state in words or icons *which* CC license  
the photos were used under!

Getting back to the comment thread on intertwingly.net, a later  
comment contained this gem:
My sarcasm detector isn't quite working, so I can't tell if the  
comment was *meant* to mock RDF, but the follow-up comment is spot on:

> It would allow the expression of properties defined by any  
> decentralised community, without the need for central coordination.  
> This includes not just CC, but every group worldwide who are  
> extending and customising CC for their own needs. Not just FOAF, but  
> groups extending it for modelling forum posts and social media (eg.  
> SIOC), or opensource projects (DOAP). Not just Dublin Core,

Interesting that you mention Dublin Core. It's a great example of why  
it's bad to just rush embedding an RDF vocabulary into HTML without a  
semantic overlap unification process like the Microformats Process.  
Most of the original DC elements duplicate native metadata facilities  
of HTML and HTTP. There will always be more content using HTML <title>  
than DC title, so consumers will be better off being able to consume  
HTML <title>. There will always be more consuming apps for HTML  
<title> than DC title, so publishers will be better off using HTML  

> but the huge range of projects that extend it to handle educational  
> metadata (which itself varies nationally), rights, aggregation,  
> classification etc. The addition of the RDFa attributes would allow  
> HTML5 to carry structured data expressed in all/any of these  
> vocabularies.

RDFa including namespace-URI mappings isn't the only possible way to  
accomplish RDF embedding into HTML5. RDFa uses CURIEs which take the  
qnames-in-content anti-pattern and keep digging the hole. I think we  
shouldn't introduce the complexity of Namespaces and qnames-in-content  
to HTML5.

Aside: The TAG has a finding saying that qnames-in-content are  

There's an obvious way how RDFa could have been adjusted to avoid the  
ills of Namespaces and qnames-in-content: using full URIs instead of  
CURIEs. N-Triples demonstrate that RDF triples can be serialized  
without a prefix binding layer.

Even if RDFa were adjusted to use full URIs, there'd still be the  
issue of objections to the additional attributes by people who not  
only think Namespaces are bad but think that embedding RDF in HTML at  
all is bad. I sent an outline of a possible way to route around this  
issue to the HTML WG and xml-dev, but my trial balloon got Warnocked:

Note: I'm not suggesting that it would be good for CC to promote  
something as complex as that. I wish CC weren't telling people to use  
RDF with any syntax (or with the NonCommercial license element, but  
that's off-topic here). However, something like the "eRDF5" trial  
balloon could work for communities who, unlike CC, aren't trying to  
meet the general public and, therefore, can afford more complexity.

Henri Sivonen
hsivonen at iki.fi

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