On 2009-01-12 23:15, Toby A Inkster wrote:
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.
Right, so some microformats brought to attention a need which HTML5
could easily solve by adding <time>. Why does this mean that RDFa
should be added?
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.
But HTML4 itself says that class can be used "for general purpose
processing by user agents", so this seems to be a weird argument. If we
introduced RDFa and it got used, would you argue you need something more
than RDFa, because it is being used for what it is specced for?
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.
Right, but is it much of an issue? If you have a hCard extractor, the
user can see easily that it's not useful data. And if doesn't follow
any of the other rules for an hCard, then the UA can safely ignore it
(e.g. it has no fields). In practice, this kind of collision seems
fairly non-problematic.
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.
Given that the only example of the microformats process needing an
addition to the HTML language has been <time>, I'm not sure that's a
conclusive proof.
Andi
