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Re: Issue #rdfms-difference-between-ID-and-about

From: Dan Connolly <connolly@w3.org>
Date: Mon, 04 Jun 2001 18:02:01 -0500
Message-ID: <3B1C1369.546B7B7D@w3.org>
To: Aaron Swartz <aswartz@upclink.com>
CC: w3c rdfcore wg <w3c-rdfcore-wg@w3.org>
Aaron Swartz wrote:
> 
> http://www.w3.org/2000/03/rdf-tracking/#rdfms-difference-between-ID-and-abou
> t
> 
>     What is the difference between using and ID attribute to 'create' a new
>     resource and an about attribute to refer to it?

As an aside, the DAML spec takes the approach that
	rdf:ID="foo"
is exactly the same as
	rdf:about="#foo"

I think that's worth saying in the spec.
(perhaps we can say that you can't have the same
ID attribute value on two different rdf:ID elements;
easy to do with XPath/schematron/xml-schema. It
might help catch some errors.)

[...]

> ** The heart of the issue:
> 
>  - ID claims to "create" a new resource, but it is assumed by some that
> referring to a resource implies its existence.[1]
> 
>  - ID claims to define an anchor ID, but it is not defined as an XML ID (and
> possibly cannot, because of interaction with bagID[2]) and the editor of the
> spec feels that it is not usable as such[3].
> 
>  - While ID is in the syntax, it is not specified in the model, which means
> that an RDF document cannot be properly "round-tripped" which I feel is an
> important goal.

I don't understand why any of these is a problem that
needs solving. How about a test case to show why it matters?

At what level do you expect to "round-trip" RDF?
I expect it at the level of n-triples. rdf:ID
is indistinguishable from rdf:about at that level.

re creating resources: that's an editorial nit. Resources just are.

re anchor ID: how is XML ID-ness relevant? anchor IDs
are a MIME type thingy, not an XML thingy.


> ** Proposals
> 
> 1) Remove/Deprecate ID from the syntax.
> 
>    The Working Group could decide to remove ID from the syntax due to
>    incompatibility/mistaken compatibility with XML IDs.

What incompatibility?

>    Cons: Breaks backwards compatibility.
> 
> 2) Allow ID to create triples in the model.
> 
>    Sergey Melnik has suggested[4] that ID create an isDefinedBy triple.
> 
>    Cons: Requires processors to change their interpretation.
> 
> I am willing to hear other proposals, but personally, I currently agree with
> proposal 2.

I'm not against proposal 2, but I find it hard to justify
as a correction to the spec. It also creates a dependency
from RDF M&S to RDFS, where there is none now.



-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 4 June 2001 19:02:11 EDT

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