darcusblog

I’ve been following the discussion about extensible metadata in HTML 5 from afar, not really having the time to get any more involved. The bottom line for one of the primary use cases I provided was, can I represent what’s embedded in my home profile and publications pages? This isn’t just about data relating to me and my pages, but linking them to other data, elsewhere. For example, I will be changing my subject pages to link to the new Library of Congress id service, such as subject headings. Can I do that in HTML 5?

The group (well, let’s be real, Ian Hickson) released a first draft of a proposal today. I haven’t really looked at it carefully and thought through all the implications, but my initial take is it seems an attempt to split the difference between RDFa and microformats. So one can encode metadata properties, for example, using either plain string tokens (the microformat way), or using URIs (the RDF/RDFa way). I might well prefer to use RDFa, but perhaps with some tweaks, the microdata proposal might well allow the most important pieces of RDFa. At least I hope so.

But there are places where there seem some arbitrary restrictions. For example, I see no way to define a microdata item’s identity as anything but local to the document (the spec only allowing local IDs; not global URIs). If I have that right, that’s a critical and arbitrary flaw, and needs to be changed.

And, as Shelley Powers points out, it’s really, really strange and arbitrary to allow one to use a “reversed DNS identifier” as a global identifier alternative to an HTTP URI, but not allow other prefix mechanisms (such as CURIEs), particularly when the common argument against namespace prefixes in general and CURIEs in particular if they are too difficult. I’d rather see all three, or only URIs.

Finally, the “item” attribute is odd. It’s effectively equivalent to the RDFa typeOf attribute, in that it allows one to type the related properties. But then a) why not just call it typeOf?, and b) related to my point about identity above, the notion of an “item” is quite ambiguous, and seems to confuse identity and type.

I’d really love if the relevant open-minded experts in this space could find time to have a f2f meeting over this proposal, and iron out these sorts of details.