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

Julian Reschke julian.reschke at gmx.de
Mon May 18 04:56:21 PDT 2009

Henri Sivonen wrote:
>> The interesting question here is whether there's a better system.
>  1) Centralized allocation of short names.

Sounds like "urn:" to me. Registry is defined in RFC 3406.

>  2) Prefixing a short name by (an abbreviation of) the name of the 
> vocabulary, which makes the probability of collision negligible once the 
> designer has googled to check the probable absence of public collisions 
> at minting time (e.g. "openid.delegate").

Too fragile for disambiguation for my taste.

>> That depends on the choice of the URI scheme.
> I guess one could use e.g. "data:,foo" URIs as a namespace URI, but why 
> not just use "foo"?

URI give you the choice of having something easily referenceable (if you 
want), or not.

>>> Problems that reverse DNS names and URIs don't have but CURIEs have:
>>> * Prefix-based indirection.
>> HTML developers regularly have to deal with a much more complicated 
>> indirection mechanism (CSS).
> This would be a persuasive argument if we were reasoning about a feature 
> we don't have experience with yet. However, experience shows 
> prefix-based indirection is too hard. If at the same time CSS isn't too 
> hard, I just have to accept the evidence from the real world even if it 
> defies reasoning.

No, I don't think we have evidence that prefix-based indirection is too 
hard. There are way to many people getting it right.

> ...
> Either @prefix or RDFa-profiles would break the network effects of the 
> deployment of outside-of-REC RDFa-in-XHTML-as-text/html, so if breaking 
> network effects is on the table in the form of @prefix and 
> RDFa-profiles, I don't see why microdata wouldn't be on the table as far 
> as network effects go.

Introducing @prefix will be much simpler to deploy than introducing a 
completely different system.

That being said, I do agree that the current situation is a mess, and 
that the RDFa-in-XHTML spec has created it.

Given the current situation, the simplest possible solution probably is 
to live with it, and use xmlns declarations in HTML for the purpose of 
RDFa as well.

BR, Julian

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