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Re: IDs? and classes

From: Charles McCathieNevile <charles@w3.org>
Date: Tue, 13 Jun 2000 18:18:14 -0400 (EDT)
To: Wendy A Chisholm <wendy@w3.org>
cc: Jason White <jasonw@ariel.ucs.unimelb.edu.au>, Web Content Accessibility Guidelines <w3c-wai-gl@w3.org>
Message-ID: <Pine.LNX.4.20.0006131812160.31946-100000@tux.w3.org>
Yes, although I need to check more carefully the syntax of CSS selectors to
see whether these are in fact legal values. (I have a nasty suspision that
there are URIs that are not, but if the characters : (colon) and / (slash)
are not allowed there is a bit of a problem. The character . (period) is not
allowed, in effect, but is not required for creating a URI.

RDF makes assertions about URIs. So if there is a URI that we can refer to,
it can create assertions in RDF. We can't create RDF about class="nav",
however.

If every element has an id then we can create information about it directly.
But that means that class information becomes an out-of-band collection of
statements about individual items, and I am not sure if that is a good thing
or not - it may be fine in the long run, but in the short term it would be a
problem for the general web. So it depends on the implementation and
acceptance..

Charles McCN

On Tue, 13 Jun 2000, Wendy A Chisholm wrote:

  Charles,
  
  Are you suggesting something along the lines of <P 
  class="http://foo.bar/definition.htm"> ?
  
  That does not seem to be the most elegant way to do things.  Isn't there 
  some way to use RDF?  Namespaces?  something else?  I agree that the URI is 
  helpful for the person who want to find out about the semantics, but how 
  would this be machine-understandable?
  
  I like Marja's original idea of include ID's on elements.  ID's could be 
  arbitrary and automatically generated for block elements.  Then, 
  annotations could be attached to any element in the document.
  
  --wendy
  
  At 04:41 AM 6/12/00 , Charles McCathieNevile wrote:
  >Actually, in the context of the "semantic web", and RDF, I have a suggestion
  >to make, which is that classes be used which are URIs - prefereably real
  >ones. This would enable two things to happen:
  >
  >  1. An author could explain, at the URI in a dereferenceable document, what
  >the class was about or for.
  >
  >  2. It would become more or less trivial to make RDF assertions about
  >classes, and therefore about how to re-use existing ones rather than create
  >new ones for each piece of content.
  >
  >In general, I am opposed to making a class if it can be avoided (for example,
  >it is better to use the existing CODE element than to produce a style class
  >for delineating code examples). In particular I would suggest that the
  >semantics of map were not extended in HTML 4.01, merely the syntax, which was
  >extended to match in the real world the semantics of the specification. But
  >that is a trivial question I guess.
  >
  >cheers
  >
  >Charles McCN
  >
  >On Mon, 12 Jun 2000, Jason White wrote:
  >
  >   Interestingly, there has been significant resistance, within this working
  >   group, to any attempt to provide common semantics to specific values of
  >   the HTML CLASS attribute, either within the guidelines or techniques
  >   documents. The basic rationale was that the semantics of CLASS values were
  >   left completely unconstrained by the HTML specification and it was
  >   desirable not to create an inconsistency, or apparent inconsistency,
  >   between HTML 4.0 and the guidelines. It was also urged that content
  >   developers should have total freedom in creating style sheets to use the
  >   CLASS attribute as they wished.
  >
  >[and so on]
  
  --
  wendy a chisholm
  world wide web consortium
  web accessibility initiative
  madison, wi usa
  tel: +1 608 663 6346
  /--
  

--
Charles McCathieNevile    mailto:charles@w3.org    phone: +61 (0) 409 134 136
W3C Web Accessibility Initiative                      http://www.w3.org/WAI
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053
Postal: GPO Box 2476V, Melbourne 3001,  Australia 
Received on Tuesday, 13 June 2000 18:18:21 GMT

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