[whatwg] Trying to work out the problems solved by RDFa

Toby A Inkster mail at tobyinkster.co.uk
Mon Jan 12 15:15:51 PST 2009

Henri Sivonen wrote:

> eRDF is very different in not relying on attributes whose qname
> contains the substring "xmlns".

eRDF is very different in that it is incredibly annoying to use in  
real world scenarios (i.e. not hypothetical "Hello World" examples).

Calogero Alex Baldacchino wrote:

> I guess closing a language to every kind of "back-door changes" may be
> in contrast with the principle of paving a cawpath. I also guess that,
> if microformats experience (or the "realworld semantics" they claim to
> be based on) had suggested the need to add a new element/attribute to
> the language, a new element/attribute would have been added.

But Microformats experience *does* suggest that new attributes are  
needed for semantics. Look at the debate around accessibility within  
Microformats which has been going on for ages. Because of the  
Microformats process of working *within* existing HTML standards it  
has not been solved, and I can't see a solution reaching consensus in  
the foreseeable future. HTML5's <time> goes part of the way to  
solving this, but it doesn't address the whole problem like RDFa's  
"content" attribute does.

Another reason the Microformat experience suggests new attributes are  
needed for semantics is the overloading of an attribute (class)  
previously mainly used for private convention so that it is now used  
for public consumption. Yes, in real life, there are pages that use  
class="vcard" for things other than encoding hCard. (They mostly use  
it for linking to VCF files.) Incredibly, I've even come across pages  
that use class="vcard" for non-hCard uses, *and* hCard - yes, on the  
same page! As the Microformat/POSHformat space becomes more crowded,  
accidental collisions in class names become ever more likely.

The Microformats community hasn't added any new attributes for  
Microformats, because that was one of the guiding principles when the  
community was established: however, that does not mean it hasn't  
shown that new attributes are needed for encoding rich semantics in  
HTML. On the contrary, I think it's proved that they are.

Toby A Inkster
<mailto:mail at tobyinkster.co.uk>

More information about the whatwg mailing list