Re: ISSUE-55: Re-enable @profile in HTML5 (draft 1)

Henri Sivonen wrote:
> On Sep 28, 2009, at 16:33, Manu Sporny wrote:
>> * RDFa uses @version, which is obsoleted in HTML5. RDFa is also becoming
>>  a FPWD, so we have to resolve how we're doing @version and @profile.
>>  Either the signaling mechanism has to change for RDFa, or we
>>  have to figure out some cross-language extended processing behavior
>>  notification mechanism.
> What does RDFa use @version for? What happens in XHTML if there is no 
> @version?

All the current RDFa-in-text/html processors I've tested have apparently 
completely ignored the absence of @version. I haven't noticed any 
RDFa-in-XHTML processors that care about it either, but I've never tried 
testing them in much detail.

Looking at some of the examples of RDFa deployment Mark gave recently in 
some other thread:

...none seem to use (or suggest using) @version, nor do they use 
@profile for RDFa.

Looking at ~425K pages from, I see 30 pages with <html 
version="XHTML+RDFa 1.0">, on 3 distinct sites.

(The next most common value is 29 pages with version="-//W3C//DTD XHTML 
1.1//EN", on about 14 distinct sites.)

Examining one page from each of those 3 sites:;-More-Cd-Box.html 
tries to use foaf and dc but it doesn't declare xmlns:foaf or xmlns:dc 
so a conforming RDFa processor will never extract any data anyway. seems to do things properly 
(except for an undeclared prefix rel="cal:website" which is presumably a 
typo of vcal). seems to do things properly.

So at least they are all actually using (or trying to use) RDFa.

Meanwhile, about 180 pages on about 90 distinct sites use rel="dc:*", 
indicating the use (or attempted use) of RDFa.

So less than 2% of pages that apparently use RDFa use @version.

This has not yet triggered the end of the world, so presumably RDFa in 
practice works fine without @version.

Philip Taylor

Received on Monday, 28 September 2009 14:27:53 UTC