RDFa about= attribute and the W3C validator

[Nathan]

I've been working on a new release of my website http://mushroomobserver.org
and trying to get all the pages to pass the W3C validator. However, a
recent change I made has me stumped. An example page is:

http://mushroomobserver.org/test/show_image.html

I'm running it through the validator with:

http://validator.w3.org/check?uri=ht...how_image.html

The error I get is:

Line 105, Column 15: there is no attribute "about".

<div about="640/#{@image.id}.jpg">

The reason I added the 'about=' attribute (and in fact the div itself)
was to use RDFa to generate the correct RDF for the Creative Commons
license I want to put the image under. I was turned onto the use of
RDFa for this purpose by the folks at Creative Commons. I think this
might have to do with the DTD I'm using for the page and perhaps there
is some additional definition file I need to load, but I'm a bit hazy
on all of this at the moment.

Any help would be most appreciated!

-Nathan

[Bergamot]

Nathan wrote:

>
Line 105, Column 15: there is no attribute "about".
<div about="640/#{@image.id}.jpg">

I was turned onto the use of
RDFa for this purpose by the folks at Creative Commons.

http://en.wikipedia.org/wiki/RDFa

Note where it says RDFa is still a proposal, which means it won't pass
validation and probably won't for a long time yet. That isn't
necessarily a reason not to use it, but it does mean that it is subject
to change so use at your own risk. See the links at the bottom of that
page for more info.

--
Berg

[Nathan]

Thanks for all the quick replies! Sounds like I've found a hairy edge
of 'doing the right thing' :-). For now, I've left the attribute in
the pages that need it, but I'm not marking them as valid and its use
is restricted tags that are only about RDFa.

I am hoping to expand my use of RDF (and probably RDFa) in the near
future, so it's good to know that this is an issue.

[Andy Dingley]

On 22 Sep, 11:37, "André Gillibert"
<[e-mail]:

Andy Dingley wrote:

[...] HTML docs (and
Appendix C XHHTML docs) using RDFa are _not_ valid, and they only
remain compliant by relying on some reliable browser error-correction
behaviour regarding the ignoring of unknwon attributes (Jukka will
butt in somewhere around this point to bad-mouth it)

Maybe they're relatively reliably supported, but they're not compliant.

What does "compliant" mean?

I suspect that you're interpreting it to mean the same as "valid",
when the RDFa spec and I take a looser (but still workable) meaning of
it. If we'd meant "valid", we'd have said "valid" (and would then have
been unable to implement it under non-XML XHTML Appendix C)