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Re: URI versus URI Reference

From: Michael Mealling <michael@bailey.dscga.com>
Date: Wed, 24 May 2000 20:20:10 -0400
To: abrahams@acm.org
Cc: michaelm@netsol.com, Tim Berners-Lee <timbl@w3.org>, John Cowan <jcowan@reutershealth.com>, xml-uri@w3.org
Message-ID: <20000524202010.B6754@bailey.dscga.com>
On Wed, May 24, 2000 at 07:52:56PM -0400, Paul W. Abrahams wrote:
> Michael Mealling wrote:
> > On Wed, May 24, 2000 at 07:19:41PM -0400, Tim Berners-Lee wrote:
> > > >> >  One would expect a URI reference to be
> > > >> > a pointer to a URI, i.e., a doubly indirect specification of a
> > > >> > resource, and not some generalization or specialization of a URI.
> > >
> > >
> > > One would, but one would be wrong. I think the term came around from
> > > some thought such as "a reference using a URI" or something...
> > > I was not very involved in the haggles about terms. It is difficult to
> > > be close to English usage at the end of a lot of specification
> > > discussions.
> >
> > Being tangentially involved in that discussion, the term came
> > from the fact that, at the time, the only place that used
> > those additional semantics of relative URIs and fragments was found
> > in hypertext references inside documents (i.e. places where a base
> > was defined and there were identified document fragments).
> 
> If I understand what you and Tim are saying, that confirms my hypothesis that
> ``URI'' and ``URI reference '' mean essentially the same thing.

Nope....

>  That is, ``a
> reference using a URI'' is close to if not identical with ``a reference 
> having the form of a URI''.
> And ``reference'' means ``a place in a document where a URI is used 
> as a hypertext reference''.

It means more than that. A URI Reference means that you have a defined base
and that fragments make sense because you know the content type of the
thing you are linking to. 2396 specifically divided the two. A 2396 'URI'
is what folx here have been calling an "absolutized URI".

I.e. the strict data type 'URI' does not allow for the relative URIs or
fragments. "URI References" are allowed to have all of those things.
The reasoning is that in many cases URIs get used by things that
aren't documents and for which relative and fragment semantics make no sense.

-MM


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Received on Wednesday, 24 May 2000 20:31:41 UTC

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