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Re: Empty URIs

From: John Cowan <jcowan@reutershealth.com>
Date: Fri, 19 May 2000 10:31:58 -0400
Message-ID: <3925505E.6109DB44@reutershealth.com>
To: Tim Berners-Lee <timbl@w3.org>, "xml-uri@w3.org" <xml-uri@w3.org>
Tim Berners-Lee wrote:

> Well, actually it wasn't empty there exactly because as you point out the spec
> [brokenly IMHO]  assigns a special meaning (of which I don't understand the
> purpose) to an empty URI [reference].

I am not sure what you mean by "purpose".  The namespace declaration
"xmlns=''" states that all un-prefixed element and attribute names within
its scope belong to no namespace at all.  This is a deeply entrenched
convention of the Namespace Rec; the howls you are hearing now will be
nothing to the howls you will hear if you try to change this.

It results, if you like, from the fact that there is no such thing as
a null URI as distinct from an empty URI reference.  When namespace
names were just URIs, then since "" is not a URI (it *is* a URI reference)
it was quite reasonable to apply it with a special meaning.  When namespace
names became (sort of) URI references, another corner case came into
being.

The Moral and Technical/Aesthetic problems are exactly the same, but this
is no corner case:  "xmlns=''" is rather a corner*stone*.

-- 

Schlingt dreifach einen Kreis um dies! || John Cowan <jcowan@reutershealth.com>
Schliesst euer Aug vor heiliger Schau,  || http://www.reutershealth.com
Denn er genoss vom Honig-Tau,           || http://www.ccil.org/~cowan
Und trank die Milch vom Paradies.            -- Coleridge (tr. Politzer)
Received on Friday, 19 May 2000 10:32:36 UTC

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